JP2017108323A - Image processing apparatus, image processing method, image reading apparatus, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate erroneous detection of a positional deviation amount, accurately acquire a positional deviation amount of an image, and generate high-quality synthesized image data.SOLUTION: An image processing apparatus 4 comprises: a similarity calculation unit 42 that calculates similarity between reference data and a plurality of pieces of comparison data, from image data in an overlapping area; a positional deviation estimation unit 43 that generates positional deviation amount data dyb from similarity data; a reliability determination unit 44 that detects an extreme value of the similarity data and, on the basis of the extreme value, sets reliability of a positional deviation amount in the overlapping area; a lateral correlation position correction unit 45 that on the basis of set reliability data, corrects positional deviation amount data in a first area, which is an overlapping area, by using positional deviation amount data in a second area, which has reliability higher than that in the first area and is an overlapping area differing from the first area; and a coupling processing unit 46 that generates synthesized image data.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image processing apparatus, an image processing method, and an image reading apparatus that combine a plurality of image data obtained by reading a reading object with a plurality of line sensors to generate composite image data corresponding to the reading object. And a program for executing processing for combining the image data.

  An image reading device that scans an object to be read by a line sensor (one-dimensional image sensor) having a plurality of image sensors arranged in a line in the main scanning direction and generates image data corresponding to the object to be read is a copier, Widely used in scanners and facsimiles. For example, Patent Document 1 describes an image reading apparatus having an imaging unit in which a plurality of line sensors are arranged in a staggered pattern or a linear pattern.

  The plurality of image data generated by the plurality of line sensors correspond to a plurality of rectangular document portions that are long in the sub-scanning direction and are obtained by cutting the document. That is, the plurality of generated image data correspond to a plurality of read images corresponding to a rectangular document portion that is long in the sub-scanning direction, and the plurality of read images are a plurality of images arranged in the main scanning direction. For this reason, the image reading apparatus compares the image portions of the overlapping region (overlapping region) where the ends of the plurality of reading images (reading ranges) of the adjacent line sensors among the plurality of line sensors overlap each other. The characteristic data is generated, and the periodicity of the overlapping region is detected by the periodicity detection unit. When the periodicity is high, the image reading device generates correction data by adding a correction amount to the characteristic data, and determines a connection position from the correction data (for example, Patent Document 1), thereby a plurality of images. The connecting position of the data in the sub-scanning direction or the main scanning direction is obtained, and a plurality of image data are connected to generate composite image data corresponding to the object to be read.

JP 2000-13589 (paragraphs 0041, 0048, 0072, FIG. 1)

  The image reading apparatus disclosed in Patent Document 1 detects a joint position where image data matches by comparing image data acquired by adjacent line sensors among a plurality of line sensors (that is, between image data). ).

  However, the image reading apparatus has a phenomenon (jitter) in which the position of the document is displaced (fluctuated) by the operation of the drive system (for example, vibration of the document transport roller, uneven rotation speed of the drive motor, and small variations in the document transport speed). ) May exist. If jitter exists, the reading position of the line sensor placed at the position affected by jitter will be displaced (fluctuated), and the deviation of the reading position of the adjacent line sensor (original position deviation) will result from jitter. The reading position shift (position shift due to jitter) is added, and a difference occurs between the image data in the overlap region acquired by the reading of the adjacent line sensors.

  In addition, when there is foreign matter (such as dust attached to the optical system) such as dust in the optical system (line sensor or lens, etc.) of the image pickup unit, the image data of the overlap areas obtained by reading of adjacent line sensors are different from each other. It will be a thing. When the size of dust attached to the optical system in the sub-scanning direction extends over several lines, there is a large difference between the image data in the overlap area obtained by reading of adjacent line sensors.

  Also, when reading an image part that has a repeated pattern such as a striped pattern or a halftone dot, there are multiple identical images in the overlap area, so there is an incorrect splice position due to the presence of jitter or optical system debris. (That is, misdetection of misalignment is likely to occur).

  Therefore, when there is jitter or optical system adhering dust in the imaging unit, if image data acquired by reading adjacent line sensors is compared, misdetection of the amount of misalignment occurs, and the connection between the image data is lost. There has been a problem that the position (or the amount of positional deviation between adjacent image data) cannot be detected with good accuracy.

  The present invention has been made to solve the above-described problems, and its purpose is to obtain a connection position between image data acquired by reading of adjacent line sensors with good accuracy, and to cope with an object to be read. The present invention provides an image processing apparatus, an image processing method, an image reading apparatus, and a program for executing a process for combining the image data.

  In the image processing device according to one aspect of the present invention, the plurality of line sensors arranged in the main scanning direction have an overlap region in which ends of reading ranges of adjacent line sensors among the plurality of line sensors overlap each other. An image processing apparatus that processes an image signal generated by an imaging unit arranged as described above, the image memory storing image data based on the image signal, and the image data read from the image memory The reference data of the reference position in the sub-scanning direction and the comparison data in the area overlapping the overlap area of the reference data are obtained from the image data of the overlap area, and the reference data and the comparison data are compared Processing is performed for a plurality of positions where the position of the comparison data is moved in the sub-scanning direction, and the reference data and the plurality of sub-data are A similarity calculation unit that calculates the similarity with the comparison data for the position in the inspection direction and outputs the similarity data indicating the similarity, and the comparison at the positions in the plurality of sub-scanning directions from the similarity data Find the position of the comparison data having the highest similarity in the data, calculate the amount of displacement based on the difference between the position of the reference data in the sub-scanning direction and the position of the comparison data having the highest similarity, A positional deviation estimation unit that outputs positional deviation amount data indicating the positional deviation amount; and a process of detecting an extreme value of the similarity degree data based on the value of the similarity degree data, and based on a result of the processing, Based on the reliability data output from the reliability determination unit, the reliability determination unit that sets the reliability of the positional deviation amount in the lap region, and outputs reliability data indicating the reliability, The positional deviation amount data in the first area, which is the overlap area, has a reliability higher than the reliability in the first area and is a different overlap area from the first area. A correlation position correction unit that corrects the positional deviation amount data in the region 2 and the adjacent line sensor among the image data read from the image memory based on the positional deviation amount data corrected by the correlation position correction unit. And a combining processing unit that generates combined image data by combining the image data read out by the above.

  In the image processing method according to another aspect of the present invention, the plurality of line sensors arranged in the main scanning direction has an overlap region in which ends of reading ranges of adjacent line sensors of the plurality of line sensors overlap each other. An image processing method for processing a generated image signal by an imaging unit arranged to have a storage step of storing image data based on the image signal in an image memory, and reading from the image memory The reference data of the reference position in the sub-scanning direction and the comparison data in the area overlapping the overlap area of the reference data are obtained from the image data of the overlap area of the image data, and the reference data and the comparison A process of comparing data is performed for a plurality of positions where the position of the comparison data is moved in the sub-scanning direction, and the reference data is Calculating a similarity between the plurality of sub-scanning direction positions and the comparison data, and outputting similarity data indicating the similarity, and calculating the plurality of sub-scanning directions from the similarity data The position of the comparison data having the highest similarity in the comparison data at the position is obtained, and the position shift is based on the difference between the position of the reference data in the sub-scanning direction and the position of the comparison data having the highest similarity. A positional deviation estimation step for calculating a quantity and outputting positional deviation amount data indicating the positional deviation amount; and a process for detecting an extreme value of the similarity degree data based on the value of the similarity degree data. A reliability determination step of setting reliability of the amount of positional deviation in the overlap region based on the reliability and outputting reliability data indicating the reliability, and the reliability determination step Based on the inputted reliability data, the positional deviation amount data in the first area which is the overlap area has higher reliability than the reliability in the first area, and the first area A correlation position correction step that is corrected based on positional deviation amount data in a second region that is another overlap region different from the region, and the positional deviation amount data that is corrected in the correlation position correction step is read from the image memory. A combination processing step of generating composite image data by combining image data read out by the adjacent line sensors in the image data.

  In the image reading apparatus according to another aspect of the present invention, the plurality of line sensors arranged in the main scanning direction have an overlap region in which ends of reading ranges of adjacent line sensors of the plurality of line sensors overlap each other. An imaging unit arranged to have, an image memory for storing image data based on an image signal generated by the imaging unit, and an overlap region in the image data read from the image memory A process of obtaining reference data at a reference position in the sub-scanning direction and comparison data in an area overlapping with an overlap area of the reference data from image data, and comparing the reference data with the comparison data. For the plurality of positions moved in the sub-scanning direction, and the reference data and the plurality of positions in the sub-scanning direction A similarity calculation unit that calculates similarity to comparison data and outputs similarity data indicating the similarity; and highest similarity among comparison data at the plurality of sub-scanning direction positions from the similarity data A position of comparison data having a degree, a position shift amount is calculated based on a difference between the position of the reference data in the sub-scanning direction and the position of the comparison data having the highest degree of similarity, and the position shift indicating the position shift amount A positional deviation estimation unit that outputs amount data, and a process of detecting an extreme value of the similarity data based on the value of the similarity data, and based on a result of the processing, the positional deviation amount in the overlap region A reliability determination unit that sets reliability and outputs reliability data indicating the reliability, and a first region that is the overlap region based on the reliability data output from the reliability determination unit The positional deviation amount data in the region is determined by the positional deviation amount data in the second region which is another overlap region different from the first region and has a higher reliability than the reliability in the first region. The correlation position correction unit to be corrected and the image data read by the adjacent line sensor among the image data read from the image memory based on the positional deviation amount data corrected by the correlation position correction unit are combined. And a combination processing unit for generating composite image data.

  In the program according to another aspect of the present invention, the plurality of line sensors arranged in the main scanning direction have an overlap region in which ends of reading ranges of adjacent line sensors among the plurality of line sensors overlap each other. A reference position reference in the sub-scanning direction from the image data in the overlap area of the image data read from the image memory storing image data based on the generated image signal by the imaging unit arranged in Data and comparison data in an area overlapping with an overlap area of the reference data, and a process of comparing the reference data and the comparison data is performed by moving a position of the comparison data in a sub-scanning direction. Performing the position, calculating the similarity between the reference data and the comparison data for the plurality of positions in the sub-scanning direction, Similarity calculation processing for outputting similarity data indicating similarity, and obtaining the position of comparison data having the highest similarity among the comparison data at the plurality of positions in the sub-scanning direction from the similarity data, A positional deviation estimation process for calculating a positional deviation amount based on a difference between a position in the sub-scanning direction of data and the position of the comparison data having the highest similarity, and outputting positional deviation amount data indicating the positional deviation amount; A process of detecting an extreme value of the similarity data based on the value of the similarity data, setting a reliability of the positional deviation amount in the overlap region based on the result of the process, and indicating the reliability Reliability determination processing for outputting degree data, and the positional deviation amount data in the first region which is the overlap region based on the reliability data output in the reliability determination processing. A correlation position correction process that corrects the error with the positional deviation amount data in the second area, which is another overlap area different from the first area, and having a higher reliability than the reliability in the first area; The combined image data is obtained by combining the image data read out by the adjacent line sensors out of the image data read out from the image memory based on the positional deviation amount data corrected by the correlation position correction processing. It is characterized by causing a computer to execute a combining process to be generated.

  According to the present invention, even when jitter or dust attached to the optical system is present in the image pickup unit, there is no erroneous detection of the connection position between the image data, and the image displacement amount in the adjacent overlap region is excellent. Since it can obtain | require with precision, the high quality synthetic | combination image data corresponding to a to-be-read object can be produced | generated.

1 is a block diagram schematically showing a configuration of an image reading apparatus according to Embodiment 1 of the present invention. (A) is a top view which shows roughly the 1st line | wire line sensor group and the 2nd line | wire line sensor group which comprise the imaging part shown by FIG. 1, (b) is a 1st row | line | column. It is a figure which shows the original as a to-be-read part read by the line sensor group and the line sensor group of the 2nd row. It is a schematic plan view which expands and shows one line sensor shown by Fig.2 (a). (A)-(c) shows the case where the original document is in close contact with the glass surface, (a) is a schematic side view of the imaging unit, (b) is a schematic plan view of the imaging unit, and A plan view of a document, (c) is a diagram conceptually showing image data obtained by reading. (A)-(c) shows the case where the original is separated from the glass surface, (a) is a schematic side view of the imaging unit, and (b) is a schematic plan view of the imaging unit and the original (C) is a diagram conceptually showing image data obtained by reading. 6 is a diagram for explaining the operation of the similarity calculation unit (when the document is in close contact with the glass surface) in the first embodiment. FIG. 6 is a diagram for explaining the operation of the similarity calculation unit according to Embodiment 1 (when the document is separated from the glass surface). FIG. (A) is a figure for demonstrating the operation | movement of the similarity calculation by the similarity calculation part in Embodiment 1, (b) is the calculated similarity data and the position shift amount of a subscanning direction. It is a figure which shows the example of a relationship. 6 is a diagram illustrating an example of a relationship between similarity data calculated by a similarity calculation unit according to Embodiment 1 and a positional deviation amount in a sub-scanning direction (when jitter or optical system attached dust exists in an imaging unit); FIG. 6 is a diagram illustrating an example of a relationship between similarity data calculated by a similarity calculation unit according to Embodiment 1 and a positional deviation amount in the sub-scanning direction (when a repeated pattern is read). FIG. Example of relationship between similarity data calculated by similarity calculation unit and sub-scanning direction displacement amount in Embodiment 1 (when repeated pattern is read, jitter or optical system attached dust exists in imaging unit) FIG. 4 is a block diagram schematically showing a configuration example of a reliability determination unit in the image processing apparatus (image processing unit) according to Embodiment 1. FIG. 3 is a block diagram schematically showing a configuration example of a lateral correlation position correction unit in the image processing apparatus according to Embodiment 1. FIG. FIG. 10 is an explanatory diagram illustrating an example of a combining operation in the combining processing unit according to the first embodiment. (A) And (b) is explanatory drawing which shows the other example of the joint operation | movement in the joint process part of Embodiment 1. FIG. 3 is a diagram conceptually illustrating image data output from a combination processing unit according to Embodiment 1. FIG. (A) And (b) is a figure which shows the example from which the position of a document changes during conveyance of an imaging part. It is a block diagram which shows roughly the example of 1 structure of the reliability determination part in the image processing apparatus which concerns on Embodiment 2 of this invention. FIG. 10 is a diagram illustrating a relationship between similarity data and a positional deviation amount in the sub-scanning direction for explaining an operation of reliability determination in the reliability determination unit according to the second embodiment. It is a block diagram which shows roughly the example of 1 structure of the horizontal correlation position correction | amendment part in the image processing apparatus which concerns on Embodiment 3 of this invention. It is a block diagram which shows roughly the example of 1 structure of the horizontal correlation position correction | amendment part in the image processing apparatus which concerns on Embodiment 4 of this invention. It is a block diagram which shows roughly the example of 1 structure of the horizontal correlation position correction | amendment part in the image processing apparatus which concerns on Embodiment 5 of this invention. It is a block diagram which shows roughly the example of 1 structure of the horizontal correlation position correction | amendment part in the image processing apparatus which concerns on Embodiment 6 of this invention. It is a block diagram which shows roughly the structure of the image reading apparatus and image processing apparatus which concern on Embodiment 7 of this invention. 18 is a flowchart schematically illustrating an example of a processing procedure performed by the arithmetic device according to the seventh embodiment. It is a side view which shows roughly the structure of the imaging part of the image reading apparatus which concerns on Embodiment 8 of this invention. FIG. 20 is a diagram illustrating an example of image data obtained by reading by an imaging unit according to the eighth embodiment. In Embodiment 8, it is a figure for demonstrating the image data after correct | amending the amount of positional deviation of the fixed amount of subscanning directions. It is a side view which shows roughly the structure of the imaging part of the image reading apparatus which concerns on Embodiment 9 of this invention.

<< 1 >> Embodiment 1
<< 1-1 >> Image Reading Apparatus 1
FIG. 1 is a block diagram schematically showing a configuration of an image reading apparatus 1 according to Embodiment 1 of the present invention. As shown in FIG. 1, the image reading apparatus 1 according to Embodiment 1 includes an imaging unit 2, an A / D (analog to digital) conversion unit 3, and an image processing unit 4. The image processing unit 4 is an image processing apparatus according to the first embodiment (an apparatus that can perform the image processing method according to the first embodiment). The image processing unit 4 includes an image memory 41 as a storage unit, a similarity calculation unit 42, a positional deviation estimation unit 43, a reliability determination unit 44, a lateral correlation position correction unit 45 as a correlation position correction unit, A combination processing unit 46.

The imaging unit 2 in the image reading apparatus 1 includes a first row of line sensor groups (for example, FIG. 2) including a plurality of (for example, n) first row line sensors arranged in a line at intervals in the main scanning direction. In (a), a line sensor group (for example, 21O or 21E) and a second line of line sensors (for example, n lines) arranged in a line at intervals in the main scanning direction (for example, n) 2E in FIG. 2A). Here, n is a positive integer. The positions of the plurality of first row line sensors in the main scanning direction are regions where the plurality of second row line sensors are not provided (that is, regions between the second row line sensors adjacent in the main scanning direction). The positions of the plurality of second row line sensors in the main scanning direction are regions where the plurality of first row line sensors are not provided (that is, in the first row adjacent in the main scanning direction). This is the position facing the area between the line sensors). As a result, the plurality of first row line sensors and the plurality of second row line sensors are arranged in a staggered pattern on the sensor substrate. The first row line sensor and the second row line sensor adjacent to each other among the plurality of first row line sensors and the plurality of second row line sensors are adjacent to each other (for example, FIG. 2 (a), sr, sl) are arranged so as to have an overlapping region (hereinafter referred to as “overlap region”, for example, A _{k, k,} etc. in FIG. 2B) overlapping in the main scanning direction. . In other words, the overlap region is a region where the ends of a plurality of read images (reading ranges) of adjacent line sensors among the plurality of line sensors overlap each other.

  The imaging unit 2 optically reads an image of a document as an object to be read and generates an electrical signal (image data) SI corresponding to the image of the document. The electrical signal (image data) SI generated by the imaging unit 2 includes first image data output from a plurality of first row line sensors constituting the first row line sensor group, and second row lines. And second image data output from a plurality of second line sensors constituting the sensor group. Note that, for example, an erect image is formed on each of the first row line sensor group and the second row line sensor group between the first row line sensor group and the second row line sensor group and the original. An optical system such as a lens may be provided.

  In the following description, an example in which the imaging unit 2 includes two lines of line sensor groups will be described. However, the present invention can also be applied when the number of lines of the line sensor groups is three or more. Further, the present invention describes a case in which line sensors are arranged in a zigzag pattern and have overlapping regions in which ends of adjacent line sensors overlap in the main scanning direction. Any arrangement other than a staggered pattern (for example, a linear pattern) may be used as long as the imaged area read by the sensor has an area that partially overlaps in the main scanning direction.

2 (a) and 2 (b) are diagrams for explaining the imaging unit 2, FIG. 2 (a) is a plan view schematically showing the imaging unit 2, and FIG. It is a top view which shows the original 60 as a to-be-read object. FIG. 2A shows, for example, a state in which an original table glass (hereinafter also referred to as “glass surface”) 26 of a copying machine is viewed from above. FIG. 3 is an enlarged schematic plan view showing _one line sensor 21O ₁ shown in FIG.

As illustrated in FIG. 2A, the imaging unit 2 includes a sensor substrate 20. A plurality of line sensors are arranged in two rows on the sensor substrate 20. In the sensor substrate 20, one end (e.g., left side) line sensor _21O 1 located odd counted _{from, ..., 21O k, ...,} 21O n is spaced linearly interval in the main scanning direction are, the line sensor _21E 1 located to the even-numbered from the _{left, ..., 21E k, ...,} 21E n is the line sensor _21O 1 located odd, _..., 21O k, ..., and 21O _n These are arranged in a straight line in the main scanning direction at different positions in the main scanning direction (X direction) so as to face each other in a staggered pattern. Here, n is an integer of 2 or more, and k is an integer of 1 to n. Line sensor _21O 1 located _{odd, ..., 21O k, ...,} 21O n is the first column line group of sensors comprising a plurality of first line sensor (or first comprises a plurality second line sensor The line sensors 21E ₁ ,..., 21E _k ,..., 21E _n located in the even-numbered line sensors are configured as a second line sensor group (or a plurality of second line sensors) (or 1st line sensor group including a plurality of first line sensors).

As shown in FIG. 2A, a plurality of first line sensors (for example, 21E ₁ ,..., 21E _k ,..., 21E _n ) belonging to the first row line sensor group are connected to the second row line. A plurality of line sensors (for example, 21O ₁ ,..., 21O _k ,..., 21O _n ) arranged so as to face the interval in the main scanning direction of the line sensors in the sensor group and belonging to the second row line sensor group, Adjacent end portions (end portions sr and sl) of the adjacent first line sensor and the second line sensor are disposed so as to face the interval in the main scanning direction of the line sensors in the first row line sensor group. Has an overlapping region overlapping in the main scanning direction.

As shown in FIG. 2A, the imaging unit 2 is moved in the sub-scanning direction (Y direction) by the transport unit 24, and reads a document 60 as a read object. Further, the transport unit 24 may be a device that fixes the imaging unit 2, transports the document 60 in the direction opposite to the sub-scanning direction (−Y direction), and reads the document 60 as an object to be read. Here, in each embodiment of the present application, a case where the imaging unit 2 moves in the direction of the arrow Dy (the arrow Dy in FIG. 2A) by the transport unit 24 will be described. The sub-scanning direction (Y direction) indicates the moving direction of the imaging unit 2 (arrow Dy in FIG. 2A), and the main scanning direction is the odd-numbered line sensors 21O ₁ ,..., 21O _k , ..., the arranging direction of 21O _n, or line sensor _21E 1 located even-numbered, _..., 21E k, ..., indicating the arrangement direction of 21E _n.

As shown in FIG. 3, the line sensor 21O ₁ includes a plurality of red photoelectric conversion elements (R photoelectric conversion elements) 26R that convert red component light of received light into electrical signals, and the received light. A plurality of green photoelectric conversion elements (G photoelectric conversion elements) 26G for converting green component light into electrical signals and a plurality of blue photoelectric conversions for converting blue component light of received light into electrical signals And an element (B photoelectric conversion element) 26B. As shown in FIG. 3, the plurality of R photoelectric conversion elements 26R are linearly arranged in the main scanning direction (X direction), and the plurality of G photoelectric conversion elements 26G are linear in the main scanning direction (X direction). The plurality of B photoelectric conversion elements 26B are linearly arranged in the main scanning direction (X direction). In the first embodiment, the line sensor having the configuration shown in FIG. 3 will be described. However, the present invention can also be applied to a line sensor in which black and white photoelectric conversion elements that do not identify colors are arranged in a line. Further, the arrangement of the plurality of R photoelectric conversion elements 26R, the plurality of G photoelectric conversion elements 26G, and the plurality of B photoelectric conversion elements 26B is not limited to the example of FIG. The line sensor 21O ₁ outputs the received information as an electric signal SI (O ₁ ). Similarly, the line sensors 21E ₁ , 21O ₂ ,..., 21O _n , 21E _n also receive the received information as electrical signals SI (E ₁ ), SI (O ₂ ),..., SI (O _n ), SI (E _n ). ). The electric signal output from the line sensor is also expressed as an electric signal SI. The electrical signal SI output from the imaging unit 2 is input to the A / D conversion unit 3.

Line sensor _21O 1 located _{odd, ..., 21O k, ...,} 21O n a line sensor _21E 1 located _{even-numbered,} ..., 21E k, ..., A 21E _n, the original 60 and partially overlapping overlap region _{a 1,1, a 1,2 reading, ..., a k, k,} a k, k + 1, a k + 1, k + 1, ..., has _{a n,} a _n. Details of the overlap area will be described later.

  The A / D converter 3 converts the electrical signal SI output from the imaging unit 2 into digital data (image data) DI. The image data DI is input to the image processing unit 4 and stored in the image memory 41 of the image processing unit 4.

FIGS. 4A to 4C are diagrams for explaining the image data DI stored in the image memory 41 in the image processing unit 4. 4 (a) is a line sensor _21O 1 located _{odd, ..., 21O k, ...,} 21O n a line sensor _21E 1 located even-numbered, _..., 21E k, ..., the optical axis 27O of 21E _n And the optical axis 27E at the position where the document 60 is present (that is, when the optical axis 27O and the optical axis 27E intersect on the glass surface 26 when the optical axes 27O and 27E are viewed in the Y direction). It is a figure which shows the positional relationship of the original document 60 and a line sensor. FIG. 4B is a diagram illustrating an example of the document 60. FIG. 4C conceptually shows image data DI corresponding to the document 60 of FIG. 4B read when the document 60 and the line sensor are in the positional relationship of FIG. 4A. .

FIG. 4A is a schematic side view of the image reading apparatus 1 and shows a state in which an apparatus (for example, a copying machine) including the image reading apparatus 1 is viewed from the side. Line sensor _21O 1 positioned to the odd-numbered as shown in FIG. _{2 (a), ..., 21O} k, ..., 21O n is also the line sensor 21O expressed, the line sensor _21E 1 located even-numbered, ..., 21E _k ,..., 21E _n are also expressed as a line sensor 21E. The reflected light of the document 60 irradiated with the illumination light source 25 such as a light emitting diode (LED) is guided to the line sensor 21O along the optical axis 27O, and is guided to the line sensor 21E along the optical axis 27E. The imaging unit 2 conveyed in the sub-scanning direction (Y direction) sequentially photoelectrically converts the reflected light of the document 60 placed on the glass surface 26 and outputs the converted electric signal SI. The A / D conversion unit 3 The electric signal SI is converted into image data DI and output.

When a document 60 as shown in FIG. 4B is sequentially photoelectrically converted by the imaging unit 2 and converted into digital data by the A / D conversion unit 3, image data DI as shown in FIG. Stored in the image memory 41. Image data DI, the line sensor _21O 1 located odd, _..., 21O k, ..., image data _DI (O 1) generated by _{21O n, ..., DI (O} k), ..., DI (O n) , 21E _k ,..., 21E _n generate image data DI (E ₁ ),..., DI (E _k ),..., DI (E _n ) generated by the even-numbered line sensors 21E ₁ ,. . In FIG. 4C, the image data DI (O _k ) and DI (O _{k + 1} ) generated by the odd-numbered line sensors 21O _k and 21O _{k + 1} and the even-numbered line sensors 21E _k and 21E _{k + 1} are included. Image data DI (E _k ) and DI (E _{k + 1} ) to be generated are shown.

Here, the overlap area _{A 1,1, A 1,2, ...,} A k, k, A k, k + 1, A k + 1, k + 1, ..., A n, n will be described. As shown in FIG. 2A, when the imaging unit 2 is conveyed in the sub-scanning direction (Y direction) and reads the document 60, the odd-numbered line sensors 21O ₁ ,..., 21O _k ,. line sensor _21E 1 positioned in the _n and the _{even-numbered,} ..., 21E k, ..., reads a portion overlapping region (overlapping region) at 21E _n. For example, the left end sl the right sr and the line sensor 21E ₁ of the line sensor 21O ₁ reads the area _{A 1, 1} of the document 60. Similarly, the right end sr of the line sensor 21 E ₁ and the left end sl of the line sensor 21 O ₂ read the areas A ₁ and _{2 of the} document 60.

Referring to the example shown in FIG. 4 (b), the left end sl the right sr and the line sensor 21E _k of the line sensor 21O _k are both read the area _{A k, k} of the original 60, and the right end sr line sensor 21E _k left sl line sensor _{21O k + 1} reads both areas _{a k} of the original _60, a _{k + 1,} the left end sl the right sr and the line sensor _{21E k + 1} of the line sensor _{21O k + 1} are both read the area _{a k + 1, k + 1} of the document 60.

Thus, image data DI _{(O k)} corresponding to the line sensor 21O _k includes digital data dr corresponding to the overlapping area _{A k, k} of the original 60, the image data DI _{(E k} corresponding to the line sensor 21E _k ) Includes digital data dl corresponding to the areas A _{k, k} of the document 60. When the original 60 is in close contact with the glass surface 26 as shown in FIG. 4A, the reading positions of the line sensor 21O and the line sensor 21E in the sub-scanning direction (Y direction) of the original 60 are Since the positions are substantially the same, as shown in FIG. 4C, the adjacent digital data dr and dl are data with no positional deviation in the sub-scanning direction (Y direction) of the document 60. In other words, the position in the sub-scanning direction (Y direction) read by the line sensor 21O and the line sensor 21E, that is, the line (hereinafter also referred to as “reading line”) is substantially the same position in the adjacent digital data dr and dl. The amount of positional deviation (number of lines) in the sub-scanning direction from the image data obtained by reading by the sensor is a value close to zero.

At this time, when the image reading apparatus 1 has a jitter that is a displacement (fluctuation) due to vibration (operation) of the drive system, or at least one optical system (line sensor or lens) in the adjacent overlap region. the foreign matter such as dust (hereinafter referred to as "jitter or optical system attached dust"), the line sensor _{21O 1, ..., 21O k,} ..., image data _DI (O 1) generated by _{21O n, ..., DI (O} k ), ..., DI (data of the overlap region in _{O n),} the line sensor _{21E 1, ..., 21E k,} ..., image data _DI (E 1 generated by the _{21E n), ..., DI (} E k), ..., in any area of the overlap area data in DI (E _n ), a reading position shift or a difference in the read image is temporarily generated, and reading is performed for each line sensor. A difference in image data (a difference in pixel data values) occurs. That is, the digital data dr corresponding to the overlap area A _{k, k} included in the image data DI (O _k ) corresponding to the line sensor 21O _k and the line sensor due to the presence of jitter or dust adhering to the optical system. image data DI area _{a k} included in _{(E k)} corresponding to 21E _k, in the digital data dl corresponding to _k, the area _{a k} of the same document _60, even if reading the _k, the image read by a period of time Therefore, a difference in the image data value occurs temporarily, or images at different positions are read.

Next, a case where the positional relationship between the original 60 and the line sensor is different from the case shown in FIG. 4A when the original 60 is separated from the glass surface 26 will be described. FIGS. 5A to 5C are diagrams for explaining the image data DI stored in the image memory 41. 5 (a) is, document 60 is floated from the glass surface 26, the line sensor _21O 1 located odd, _..., 21O k, ..., the line sensor 21E ₁ positioned to the optical axis and the even-numbered 21O _n ,..., 21E _k ,..., 21E _n are diagrams illustrating the positional relationship between the document 60 and the line sensor when the document 60 is located at a position different from the position where the optical axes intersect. FIG. 5B is a diagram showing an example of the original 60. FIG. 5C is an original 60 shown in FIG. 5B when the original 60 and the line sensor are in the positional relationship shown in FIG. 5A. It is a figure which shows notionally the image data DI corresponding to.

Even when the document 60 is lifted off the glass surface 26, the positional relationship between the line sensor and the document 60 when viewed in plan is not changed. That is, each line sensor acquires data at the same position in the main scanning direction (X direction) when the document 60 is lifted from the glass surface 26 and when it is in close contact with the glass surface 26. Thus, in FIG. 5 (b), the as in the case of FIG. 4 (b), the left sl the right sr and the line sensor 21E _k of the line sensor 21O _k reads both areas _{A k} of the original _60, a _k, a line rightmost sr and the line sensor _{21O k + 1} of the left sl sensor 21E _k are both reading area _{a k} of the original _60, a _{k + 1,} the line sensor _{21O k + 1} of the rightmost sr and the line sensor _{21E k + 1} of the left sl are both regions of the document 60 Read A _{k + 1, k + 1} .

On the other hand, as shown in FIG. 5A, when viewed from the side view of the imaging unit 2, since the document 60 is floating from the glass surface 26, the odd-numbered line sensors 21 _</ b> O ₁ ,. , ..., the line sensor _21E 1 to the optical axis 27O of 21O _n is located at the position and the even-numbered intersecting the document 60, _..., 21E k, ..., a position where the optical axis 27E intersects the document 60 21E _n different. Therefore, when the document 60 is floating from the glass surface 26, the reading position is different for each line sensor in the sub-scanning direction (Y direction). This is because the line sensors 21E ₁ ,..., 21E _k ,... Positioned evenly because each line sensor sequentially performs photoelectric conversion when the imaging unit 2 is conveyed in the sub-scanning direction (Y direction). , 21E _n is the line sensor _21O 1 located odd, _..., 21O k, ..., compared to 21O _n, is because so that acquiring an image of the same position temporally delayed. Accordingly, as shown in FIG. 5C, the image data DI (O _k ) and DI (O _{k + 1} ) corresponding to the odd-numbered line sensors 21O _k and 21O _{k + 1} and the even-numbered line sensor 21E. _The image data DI (E _k ) and DI (E _{k + 1} ) corresponding to _{k 1} and 21E _{k + 1} are shifted in position (line) in the sub-scanning direction and compared with (image data DI (O _k ) and DI (O _{k + 1} ). Data DI (E _k ) and DI (E _{k + 1} ) are shifted downward in the drawing) and stored in the image memory 41. In other words, the position in the sub-scanning direction (Y direction) read by the line sensor 21O and the line sensor 21E is different in the position (line) in the sub-scanning direction in the image memory 41 between the adjacent digital data dr and dl. Thus, a positional deviation amount (number of lines) in the sub-scanning direction from the image data obtained by the reading of the line sensor occurs.

Similarly to the cases of FIGS. 4A to 4C, when there is jitter or optical system adhering dust in the imaging unit 2, the odd-numbered line sensor 21 _< / b> O _k and the even-numbered line are arranged. in addition to the difference in the reading position of the sensors 21E _k, the overlap area _{a k} included in the image data DI _{(O k)} corresponding to the line sensors 21O _k, and digital data dr corresponding to _k, corresponding to the line sensor 21E _k With the digital data dl corresponding to the area A _{k, k} included in the image data DI (E _k ), there is a temporary difference in the value of the image data, or images at different positions are read.

<< 1-2 >> Image Processing Unit 4
The image processing unit 4 generates the first image data generated from the outputs from the plurality of line sensors in the first row of line sensor groups and the first image data generated from the outputs from the plurality of line sensors in the second row of line sensor groups. An image memory 41 for storing the second image data. In addition, the image processing unit 4 performs predetermined sub-scanning on image data in an overlap area of image data (first image data and second image data) DI stored in the image memory 41. The process of comparing the reference data of the position in the direction (also referred to as sub-scanning position or line) with the comparison data of the predetermined number of lines in the same overlap area read overlapping with the reference data A similarity calculation unit 42 is provided for calculating the similarity between the reference data and the comparison data at a plurality of positions in the sub-scanning direction (that is, the comparison data for a plurality of lines). Further, the image processing unit 4 obtains the position in the sub-scanning direction of the comparison data having the highest similarity among the similarities between the reference data and the comparison data in the plurality of lines, and the position from the obtained position is determined. A misalignment estimation unit 43 that calculates the misalignment amount is provided. The image processing unit 4 also includes a reliability determination unit 44 that determines (sets) the reliability of the positional deviation amount detected in each overlap region from the value of the similarity data Dist indicating the similarity in the overlap region. The amount of misalignment in the overlap region with low reliability (having low reliability) is higher than that of other adjacent overlap regions with high reliability (having higher reliability than the low reliability). And a lateral correlation position correcting unit 45 for correcting based on the positional deviation amount of the lap region. Further, the image processing unit 4 reads the image data from the image memory 41 by changing the connection position based on the corrected positional deviation amount, and combines the first image data and the second image data. It has.

  The image processing unit 4 calculates the degree of similarity by comparing the reference data and the comparison data in the overlap region with respect to the image data in the overlap region in the image data DI stored in the image memory 41. The positional deviation amount is calculated from the position in the sub-scanning direction of the comparison data having the highest similarity among the similarities, and the positional deviation amount detected in each overlap region is determined from the value of the similarity data Dist. Set the degree. Further, the image processing unit 4 calculates the positional deviation amount in the overlap region having a low reliability out of the obtained reliability, and the position in the region having a high reliability in the other adjacent overlap regions. Correction is performed based on the shift amount, image data is read from the image memory 41 based on the corrected positional shift amount, and a combination process is performed on the read image data. Hereinafter, the configuration of the image processing unit 4 will be described in detail with reference to FIG.

<< 1-3 >> Similarity Calculation Unit 42
Similarity calculation unit 42, the image data in the overlap area of the image memory 41, i.e., in the image data DI, the position Y _m and its surrounding (Y direction M lines of a predetermined sub-scanning direction (Y-direction) Image data for each interval and in the main scanning direction (X direction) is read as reference data MO, and the same overlap area read overlapping with reference data MO is sub-scanning direction (Y direction) of reference data MO. predetermined search range before and after the line of position _{Y m} of (dY = -y~ + y) _(i.e., the range from _Y m -y to _Y m + y) position and its neighborhood (Y-direction M each line interval and The image data in the X direction) is read out as comparison data ME, and the reference data MO and comparison data ME having a predetermined number of lines are received. Here, M is a positive integer. The similarity calculation unit 42 performs a process of comparing the reference data MO and the comparison data ME for a plurality of positions within the search range from the positional deviation amount dY = −y to dY = + y, and calculates the similarity data Dist. The similarity data Dist is output to the misregistration estimation unit 43 and the reliability determination unit 44.

  6 and 7 are diagrams for explaining the positions on the overlap region in the image data DI where the reference data MO and the comparison data ME input to the similarity calculation unit 42 are located.

FIG. 6 is a diagram corresponding to FIG. 4C (when the document 60 is in close contact with the glass surface) and shows the positional relationship between the reference data MO and the comparison data ME on the image data DI. The reference data MO is image data at the position Y _m (line Y _m ) in the sub-scanning direction (Y direction), and the comparison data ME has a positional deviation amount dY within the search range (dY = −y to + y). Image data. FIG. 7 is a diagram corresponding to FIG. 5C (when the document is separated from the glass surface), and reference data MO at a position Y _m (line Y _m ) in the sub-scanning direction (Y direction); The positional relationship of the comparison data ME which is image data in which the positional deviation amount dY falls within the search range (dY = −y to + y) is shown.

As shown in FIGS. 6 and 7, the reference data MO at the position Y _m in the sub-scanning direction (Y direction) is the line in the overlap region dr of the image data DI (O _k ) corresponding to the line sensor 21O _k. This is image data corresponding to peripheral image data centered on Y _m , and is MO (O _k , dr, Y _m ) in the figure. The comparison data ME that is image data in which the positional deviation amount dY falls within the search range (dY = −y to + y) is the line Y in the overlap region dl of the image data DI (E _k ) corresponding to the line sensor 21E _k. A line within a search range (dY = −y to + y) centered on _m (that is, a range from the line Y _m −y to the line Y _m + y) and its surrounding image data, and the image data ME in the figure (E _k , dl, Y _m ). The comparison data ME is image data of a line within the search range (dY = −y to + y), and the comparison data ME is wider in the sub-scanning direction (Y direction) than the reference data MO. 6 and 7, the reference data MO (O _k , dr, Y _m ) and the comparison data ME of the overlap region dr of the image data DI (O _k ) and the overlap region dl of the image data DI (E _k ). Similarly to the case of (E _k , dl, Y _m ), the reference data MO () is sequentially applied to the overlap region dl of the image data DI (O _{k + 1} ) and the overlap region dr of the image data DI (E _k ). O _{k + 1} , dl, Y _m ) and comparison data ME (E _k , dr, Y _m ) are compared with the overlap region dr of the image data DI (O _{k + 1} ) and the overlap region dl of the image data DI (E _{k + 1} ). reference data _{MO (O k + 1, dr} , Y m) and the comparison data _{ME (E k + 1, dl} , Y m) is, the similarity calculation as image data in the overlap region 42 is input to.

8A and 8B are diagrams for explaining the similarity calculation operation in the similarity calculation unit 42 according to the first embodiment, and the calculated similarity data and the amount of positional deviation in the sub-scanning direction. It is a figure which shows the example of a relationship. 8A and 8B show a case where reference data MO (O _k , dr) and comparison data ME (E _k , dl) centered on the detection reference line Y _m are input to the similarity calculation unit 42. Is shown. In FIG. 8A, the similarity calculation unit 42 first compares the input reference data MO (O _k , dr) with the comparison data ME (E _k , E within the search range (dY = −y to + y). A plurality of image data ME (E _k , dl, dY) having the same size as the reference data MO (O _k , dr) (the same width bh line in the sub-scanning direction) is extracted from dl). Search range dY is a position deviation amount in the sub-scanning direction between reference data MO _(O k, dr), takes a value within the range of -y~ + y around the detection reference line _{Y m.} And reference data MO _(O k, dr) data at the same position as the center position is detected reference line _{Y m} of the image data _{ME (E k, dl, 0} ) and a one line shift data ME _{(E k} , Dl, 1) and further shifted by one line, the data shifted by y lines is set as image data ME (E _k , dl, + y), and the data shifted by y lines in the reverse direction is image data ME (E _k , Dl, -y).

Next, the similarity calculation unit 42 includes image data ME (E _k , dl, −y) to ME (E _k , dl,) in the reference data MO (O _k , dr) and the comparison data ME (E _k , dl). + Y), and similarity data Dist (O _k , E _k ) indicating the calculated similarity, that is, similarity data in the overlap region between the line sensors 21O _k and 21E _k is generated. . Since the similarity calculation unit 42 has the same size as each of the reference data MO (O _k , dr) and each of the image data ME (E _k , dl, −y) to ME (E _k , dl, + y), For example, the sum of absolute values of differences for each pixel between the reference data MO (O _k , dr) and each of the image data ME (E _k , dl, −y) to ME (E _k , dl, + y), or The sum of squares of differences for each pixel is calculated as similarity, and similarity data Dist (O _k , E _k , dY) indicating the calculated similarity, that is, in the overlap region between the line sensors 21O _k and 21E _k Output as similarity data. Similarly, the similarity calculation unit 42 includes the next reference data MO (O _{k + 1} , dl) and comparison data ME (E _k , dr), the reference data MO (O _{k + 1} , dr) and the comparison data ME (E _{k + 1} , dl). ),... Are sequentially calculated, and similarity data Dist (O _{k + 1} , E _k , dY), Dist (O _{k + 1} , E _{k + 1} , dY),.

In FIG. 8A, the image data ME (E _k , dl is shifted by one line as the positional deviation amount dY from the comparison data ME (E _k , dl) within the search range (dY = -y to + y). , DY) to calculate the similarity (similarity data Dist), but by interpolating from the image data of the previous and subsequent lines, the position in the sub-scanning direction between the lines (sub-line and The similarity data Dist can also be generated by calculating the similarity with the reference data MO.

FIG. 8B shows the image data ME (E _k , d) of the reference data MO (O _k , dr) centered on the detection reference line Y _m and the comparison data ME (E _k , dl) in the similarity calculator 42. dl, −y) to ME (E _k , dl, + y) similarity data Dist (O _k , E _k , in the search range (dY = −y to + y) of the positional deviation amount dY when the similarity is calculated. An example of the value of (dY) is shown. In FIG. 8B, the broken line Dist0 is similarity data Dist (O _k , E _k , dY) corresponding to FIGS. 4A to 4C and FIG. 6, and the solid line Dist1 is FIG. Similarity data Dist (O _k , E _k , dY) corresponding to (c) and FIG. In FIG. 4 (a) ~ (c) and 6, the line sensor _21O 1 located odd, _..., 21O k, ..., the line sensor _21E 1 located to the even-numbered and _{21O n, ..., 21E k,} ... since the 21E _n is reading the same position in the sub-scanning direction (Y-direction), not shifted even that data. Therefore, as shown by the broken line Dist0 in FIG. 6B, the Dist value is minimum and the similarity is high (that is, the dissimilarity is low) at the position of dY = 0. Further, in FIG. 5 (a) ~ (c) and 7, since the original 60 is away on the glass surface 26, the line sensor _21O 1 located odd, _..., 21O k, ..., to 21O _n line sensor _21E 1 located numbered for, _..., 21E k, ..., read image 21E _n is the sub-scanning direction of the positional deviation in the downward direction of the image, at the position of the positive value (dY = + a) , Dist is the smallest and the similarity is the highest (ie, the dissimilarity is the lowest).

  As described above, when jitter or optical system adhering dust exists in the imaging unit 2, the difference between the image data read for each line sensor (the value of the pixel data) is included in the image data of the overlap region in the image data DI. Difference) occurs. In other words, in an image to be read in a certain period, the reading position is deviated from the original position, a difference is temporarily generated in the value of the image data, or an image at a different position is read, and the value of the similarity data Dist Is a value that varies from the original value. For this reason, the position where the similarity is the highest may be temporarily shifted, or the value of the similarity data Dist may be increased (similarity is decreased).

<< 1-4 >> Position Deviation Estimation Unit 43
The positional deviation estimation unit 43 receives the similarity data Dist for the positional deviation amounts dY of a plurality of lines within the search range (dY = −y to + y) output from the similarity calculation unit 42. The positional deviation estimation unit 43 outputs the positional deviation amount dY corresponding to the data having the highest similarity among the similarity data Dist of the plurality of lines as the positional deviation amount data dyb to the lateral correlation position correction unit 45.

  For example, in FIG. 8B, when the value of the similarity data Dist is minimum (ie, the similarity is high and the dissimilarity is low) at the position of dY = 0 as indicated by the broken line Dist0, the positional deviation estimation is performed. The unit 43 sets dY = 0 as the positional deviation amount data dyb. Further, when the value of the similarity data Dist is minimum at the position of dY = + a as indicated by the solid line Dist1 (that is, the similarity is the highest and the dissimilarity is the lowest), the positional deviation estimation unit 43 Let dY = + a be the positional deviation amount data dyb.

<< 1-5 >> Reliability Determination Unit 44
As described above, when there is jitter or optical system adhering dust in the imaging unit 2, a difference occurs between the image data of the adjacent overlap areas, and the value of the similarity data Dist in the overlap area is the original value. That is, a value including noise components caused by jitter or dust attached to the optical system. For example, the position where the similarity increases due to jitter (the value of the similarity data Dist decreases) temporarily shifts by several lines, or the value of the similarity data Dist increases due to dust adhering to the optical system (the similarity decreases). Sometimes lower).

FIG. 9 illustrates similarity data jDist (O _k , E _k , dY) and sub-scanning that are calculated when there is jitter or optical system adhering dust in the imaging unit 2 in the similarity calculation unit 42 according to the first embodiment. It is a figure which shows the example of the relationship with the positional offset amount dY of a direction. In FIG. 9, a broken line Dist0 indicates an example of the similarity data Dist calculated by the similarity calculation unit 42 when the jitter is sufficiently low and there is no dust attached to the optical system. In FIG. 9, a solid line jDist0 shows an example of the similarity data Dist calculated by the similarity calculator 42 when the influence of jitter at the time of reading or the dust attached to the optical system is significant. In the normal case (when the influence of jitter and dust adhering to the optical system is small), the value of the similarity data Dist becomes minimum at the position of the positional deviation amount dY = 0 as shown by the broken line Dist0 (that is, the similarity degree). Is the maximum and the dissimilarity is minimum), and the position of the minimum similarity is one position.

  On the other hand, when the jitter increases, the reading position of the line sensor arranged at a position susceptible to the jitter is temporarily shifted, and the original reading position between the line sensors is different from the reading image in the overlap area. Different reading position shifts due to jitter occur, and there is a difference between images in adjacent overlapping regions. Further, when there is an optical system adhering dust in the optical system (line sensor or lens of the imaging unit 2) in at least one of the adjacent overlap areas, the read image of the adjacent overlap area Are different from each other, and there is a large difference between the two. Therefore, as indicated by the solid line jDist0 in FIG. 9, the position of the image in the sub-scanning direction is shifted, for example, the value of the solid line jDist0 is small at the position of dY = aj, but the value of the similarity data Dist is overall. Increased (ie, the degree of similarity decreases and the degree of dissimilarity increases). In the case of FIG. 9, at the position of dY = aj, the value of the solid line jDist0 is the smallest and the degree of similarity is the largest, but the degree of similarity at the position of dY = aj and the lines before and after (periphery in the sub-scanning direction) The difference with the similarity in is small. Therefore, in such a case, the position of dY = aj may not be reliably identified as the position with the minimum similarity, and erroneous detection is likely to occur.

FIG. 10 shows an example of the relationship between the similarity data Dist2 and the positional deviation amount dY in the sub-scanning direction when the similarity calculation unit 42 according to the first embodiment reads a repeated pattern in which the same pattern is repeated as an object to be read. FIG. For example, when an image portion that is a repeated pattern such as a striped pattern or a halftone dot is read by the imaging unit 2, there are a plurality of positions that are the same image in the overlap region, and the similarity calculation unit 42 determines the similarity. As shown in FIG. 10, the value of the similarity data Dist2 (O _k , E _k , dY) when calculating the position of the similarity data is minimized (that is, the similarity becomes higher). There are multiple. For example, the similarity data in the repetitive pattern has a minimum value of the similarity data Dist2 at positions dY = a1, dY = a2, and dY = a3 as in the similarity data Dist2 in FIG. High similarity and low dissimilarity). At this time, the misregistration estimation unit 43 calculates the misregistration amount dY corresponding to the data with the highest similarity in the similarity data Dist2 in the misregistration amounts dY of the plurality of lines output from the similarity calculation unit 42. The positional deviation amount data dyb is used. However, when there are a plurality of minimum points in the value of the similarity data, the position deviation estimation unit 43 determines whether the position of the minimum value among the plurality of minimum points or the original deviation of the reading position is dY = 0 or dY. The position where the value of the similarity data Dist is the smallest at the position closest to + a is regarded as the highest similarity, and is referred to as positional deviation amount data dyb.

FIG. 11 shows the similarity data calculated by the repetitive pattern and the positional deviation amount dY in the sub-scanning direction when jitter or optical system attached dust is present in the imaging unit 2 in the similarity calculation unit 42 of the first embodiment. It is a figure which shows the example of these relationships. When jitter or optical system adhering dust is present when reading a repetitive pattern, the reading position of the line sensor arranged at a position where the influence of jitter or optical system adhering dust is large is temporarily changed as in the case described with reference to FIG. As a result, the image data in the adjacent overlap areas are different from each other, and a large difference is generated between the image data. FIG. 11 shows an example of the value of the similarity data jDist (O _k , E _k , dY) in the read image of the repetitive pattern when there is jitter or dust attached to the optical system. In FIG. 11, a broken line Dist2 is similarity data Dist when there is no influence of jitter or optical system adhering dust during reading, and a solid line jDist2 is similar when there is an influence of jitter or optical system adhering dust during reading. It is an example of degree data.

  As shown in FIG. 11, when there is an influence of jitter at reading or dust adhering to the optical system, the position where the value of the similarity data becomes minimum is dY = aj1, dY = aj2, and dY, as indicated by a solid line jDist2. = Aj3, and a shift occurs compared to the broken line Dist2, and the value of similarity data increases as a whole (that is, the similarity decreases and the dissimilarity increases). The position at which the value of the similarity data is minimum due to the value of the similarity data (solid line jDist2) at the positions of dY = aj1, dY = aj2, and dY = aj3 is shown in FIG. 11, and the similarity is at the position of dY = aj1. A false detection may occur where the data value is determined to be minimum (ie, the similarity is maximum). Also, as shown by the solid line jDist0 in FIG. 9, even when the difference in similarity at each line position is small and the minimum position cannot be reliably detected, erroneous detection is likely to occur.

  Therefore, the reliability determination unit 44 in FIG. 1 determines (sets) the reliability of the positional deviation amount dY detected in each overlap region from the value of the similarity data Dist in the overlap region.

The reliability determination unit 44 uses the similarity data Dist in the positional deviation amounts dY of a plurality of lines within the search range (dY = −y to + y) output from the similarity calculation unit 42, that is, overlaps of the line sensors. Similarity data Dist (O _k , E _k , dY), Dist (O _{k + 1} , E _k , dY), Dist (O _{k + 1} , E _{k + 1} , dY),. The reliability determination unit 44 calculates the magnitude of the value of the similarity data Dist in each position from the similarity data Dist for a plurality of lines within the search range (dY = −y to + y) of the positional deviation amount dY. Whether or not there is an extreme value (for example, a position where the value changes from decreasing to increasing) is detected near the position where the value of the similarity data Dist becomes small (that is, processing for detecting the extreme value is performed). Based on the result, the reliability of the positional deviation amount is determined (set), and reliability data pcnt indicating the set reliability is output.

  FIG. 12 is a block diagram schematically illustrating a configuration example of the reliability determination unit 44. The reliability determination unit 44 in FIG. 12 compares the similarity data Dist in the positional deviation amounts dY of the plurality of lines within the search range (dY = −y to + y) output from the similarity calculation unit 42 with the threshold value Ndy. The candidate Mpo of the position where the value of the similarity data Dist is small and the minimum is obtained, the position having the extreme value is detected from the candidate Mpo, and the reliability is set from the value of the similarity data Dist and the presence / absence of the extreme value And output as reliability data pcnt indicating the set reliability.

  As illustrated in FIG. 12, the reliability determination unit 44 includes a threshold setting unit 441, a similarity comparison unit 442, an extreme value detection unit 443, and a reliability setting unit 445.

Similarity data Dist for the positional deviation amounts dY of a plurality of lines within the search range (dY = −y to + y) output from the similarity calculation unit 42 includes a threshold setting unit 441, a similarity comparison unit 442, and an extreme value. This is input to the detection unit 443. The threshold value setting unit 441 has similarity data Dist having a small value and a minimum position candidate for the similarity data Dist of a plurality of lines within the search range (dY = −y to + y) of the positional deviation amount dY. A threshold value Ndy for determining the value of Dist is set. The similarity data Dist is a sum of absolute values of differences for each pixel of the reference data MO (O _k , dr) and the image data ME (E _k , dl, −y) to ME (E _k , dl, + y), or Since the sum of squares of the differences for each pixel is calculated as the similarity, the value for determining that the similarity data is the minimum (that is, the highest similarity and the lowest dissimilarity) is 0. For example, A value within a range of Ndy = 0 to Na having a predetermined width from 0 is set as a threshold value. This Na may be a value determined in advance in consideration of noise of an image read from the line sensor. Further, Na may be set to calculate an average value of the similarity data Dist within the search range (dY = −y to + y) and target a value smaller than this average value. Thereby, a threshold value can be set adaptively regardless of the presence or absence of noise.

  The similarity comparison unit 442 receives the similarity data Dist and the threshold value Ndy output from the threshold setting unit 441, compares the similarity data Dist with the threshold value Ndy, and the value of the similarity data Dist is small and becomes the minimum. A position candidate is obtained, and the position data Mpo is output. The similarity comparison unit 442 obtains a position where the similarity data Dist of a plurality of lines within the search range (dY = −y to + y) of the positional deviation amount dY is smaller than the threshold value Ndy output from the threshold setting unit 441, It is assumed that the value of the similarity data Dist is small and is a minimum position candidate.

  The extreme value detection unit 443 receives the similarity data Dist and the position data Mpo output from the similarity comparison unit 442. The position data Mpo indicates a position candidate where the value of the similarity data Dist is small and becomes the minimum. The extreme value detection unit 443 detects, from the position data Mpo and the similarity data Dist at the surrounding positions, whether the similarity data of the position data Mpo is an extreme value that changes from decrease to increase, and the extreme value The extreme value determination result LMd indicating the position to be output and the similarity data Dsl at that position are output. In addition, when there is no extreme value, the extreme value detection unit 443 outputs information indicating no extreme value as the extreme value determination result LMd.

  For example, in the case of FIG. 9, the extreme value detection unit 443 has an extreme value when the value of the similarity data Dist0 is dY = 0, and thus the extreme value detection unit 443 has the extreme value determination result LMd and dY = 0. Similarity data Dsl is detected. On the other hand, when the influence of jitter at reading or dust attached to the optical system occurs, the extreme value detection unit 443 does not determine that the similarity data jDist0 has an extreme value. That is, in FIG. 9, the value of the similarity data Dist becomes small at the position of dY = aj, but decreases when the difference between the similarity of the previous and subsequent lines at the position of dY = aj is small. If it is not an extreme value that changes from to, it cannot be determined as the minimum value. Further, depending on the setting of the threshold value Ndy, the similarity comparison unit 442 may not be obtained as a candidate for the position where the value of the similarity data Dist is small due to the comparison between the similarity data jDist and the threshold value Ndy.

  Further, in the case of reading a repeated pattern as shown in FIG. 11, the extreme value detection unit 443 detects a plurality of extreme values positions from the similarity data Dist, and the extreme value determination result LMd is similar to the position. The degree data Dsl is output.

  The reliability setting unit 445 receives the extreme value determination result LMd output from the extreme value detection unit 443 and the similarity data Dsl of the position, determines (sets) the reliability of the positional deviation amount, and sets the reliability Is output reliability data pcnt. The reliability setting unit 445 sets the reliability from the extreme value determination result LMd and the similarity data Dsl at that position. For example, the reliability setting unit 445 sets the reliability data pcnt based on the number of extreme values indicated by the extreme value determination result LMd. When the extreme value determination result LMd is one position and the value of the similarity data Dsl at that position is smaller than a predetermined reference value, the reliability setting unit 445 determines that the reliability is high and the reliability data pcnt = 1. Is set, and the extreme value determination result LMd indicates that there is no extreme value, the reliability is low and the reliability data pcnt = 0. The reliability setting unit 445 sets the reliability data pcnt as the number of extreme values (a value of 2 or more) with the reliability as an intermediate value when the extreme value determination result LMd has a plurality of extreme values. For example, the reliability setting unit 445 sets 1 as the reliability in the first case where it is determined that the reliability is high, and sets 0 as the reliability in the second case where it is determined that the reliability is low. In the third case where the reliability is determined to be intermediate between the first case and the second case, 2 is set as the reliability.

  Moreover, although the case where the reliability data pcnt is set based on the number of extreme values indicated by the extreme value determination result LMd has been described, the reliability setting unit 445 is reliable when the extreme value determination result LMd indicates one position. When the reliability data pcnt = 1 is set and the extreme value determination result LMd indicates that the extreme value determination result LMd does not have an extreme value, or the extreme value determination result LMd has a plurality of extreme values, The reliability data pcnt = 0 may be set on the assumption that the reliability is low. In this case, the reliability setting unit 445 sets 1 as the reliability in the first case where the reliability is determined to be high, and the second determines that the reliability is lower than in the first case. In this case, 0 is set as the reliability.

  The reliability setting unit 445 outputs reliability data pcnt indicating the reliability of the positional deviation amount set based on the extreme value determination result LMd and the extreme position similarity data Dsl indicated by the extreme value determination result LMd. To do. For this reason, the image processing unit 4 determines from the reliability data pcnt a case where there is an influence of jitter at the time of reading or dust attached to the optical system, and the similarity data Dist changes from the original value. It is possible. Further, the image processing unit 4 can also determine from the reliability data pcnt even when the extreme value determination result LMd has a plurality of extreme values as in the case of a repetitive pattern. Furthermore, the image processing unit 4 can determine from the reliability data pcnt also when there is a possibility that the position where the minimum value is changed due to the change in the similarity data Dist.

<1-6> Lateral Correlation Position Correction Unit 45
The lateral correlation position correction unit 45 receives the reliability data pcnt output from the reliability determination unit 44 and the positional deviation amount data dyb output from the positional deviation estimation unit 43. Based on the reliability data pcnt output from the reliability determination unit 44, the lateral correlation position correction unit 45 obtains the positional deviation amount data in the first area, which is the overlap area, from the reliability in the first area. Also, the correction is performed based on the positional deviation amount data in the second area, which is another overlap area different from the first area. For example, the lateral correlation position correction unit 45 uses the overlap area with high reliability in the adjacent overlap areas as the positional shift amount in the overlap area determined to be low with reliability data pcnt. Is corrected based on the amount of misregistration, and the corrected misregistration amount Dt is output to the combination processing unit 46.

FIG. 13 is a block diagram schematically showing a configuration example of the lateral correlation position correction unit 45. The lateral correlation position correction unit 45 in FIG. 13 is arranged around the overlap area (first area) with respect to the position shift amount data dyb for the overlap area of each line sensor output from the position shift estimation unit 43. Position shift amount data dyb indicating the position shift (dY) in the sub-scanning direction obtained in a certain other overlap area (second area) (area located on the left and right of the other end), and another overlap area Based on the reliability data pcnt in the (second area), a correction position of the amount of displacement in the overlap area (first area) is generated, and the corrected position in the overlap area (first area) A deviation amount Dt is obtained. For example, when the overlap region (first region) is the overlap region _{Ak, k + 1} in FIGS. 4B and 5B, the corrected positional deviation amount Dt is generated. The other overlap regions (second regions) used in the above are the other overlap regions A _{k, k} and A _{k + 1, k + 1} in FIGS. 4B and 5B.

  In this way, the second region can include at least one of the overlap regions immediately adjacent to the first region. When referring to the two second areas, either the positional deviation amount obtained in the second area or the positional deviation amount obtained in the second area as the corrected positional deviation amount Dt. The average value of can be used.

Note that the “region located on the left and right of the other end” means, for example, that the overlap region (first region) is the overlap region _{Ak, k + 1} in FIGS. 4B and 5B. In some cases, an area corresponding to another overlap area (second area) used for generating the corrected positional deviation amount Dt (that is, the overshoot in FIGS. 4C and 5C). The dl of the region DI (E _k ) corresponding to the overlap region A _{k, k} and the dr of the region DI (O _k ), and the dl and region DI (E _{k + 1} ) of the region DI (E _{k + 1} ) corresponding to the overlap region A _{k + 1, k + 1} Dr) of O _{k + 1} ).

  As described above, the second region can include at least one of the overlap regions immediately adjacent to the first region and at least one of the overlap regions adjacent to the second region from the first region. When referring to the four second areas, the positional deviation amount Dt after correction is either the positional deviation amount obtained in the second area or the positional deviation amount obtained in the second area. The average value of can be used. It should be noted that the number of overlap regions referred to for calculating the corrected positional deviation amount may be a larger number (5 or more).

In addition, the “region located on the left and right of the other end” means that the overlap region (first region) is the overlap region _{Ak, k + 1} in FIGS. 4B and 5B. In addition, a region (that is, two overlap regions A _{k−1, k} and A _{k, k} ) corresponding to another overlap region (second region) used for generating the corrected positional deviation amount Dt. And DI (E _k−1 ), DI (O _k ), DI (E _k ), DI (O _{k + 1} ), DI (in the areas corresponding to the _two overlapping areas A _{k + 1, k + 1} and A _{k + 1, k + 2} E _{k + 1} ), four overlapping regions, or more regions).

  As illustrated in FIG. 13, the lateral correlation position correction unit 45 includes a correction position generation unit 451, a combined position determination unit 452, a one-line position holding unit 453, and a comparison unit 454.

  The corrected position generation unit 451 receives the reliability data pcnt output from the reliability determination unit 44 and the positional deviation amount data dyb output from the positional deviation estimation unit 43. The correction position generation unit 451 leaves the positional deviation amount data dyb output from the positional deviation estimation unit 43 as it is in the overlap region where the reliability is high and the minimum value is one by the reliability data pcnt. Further, the correction position generation unit 451 determines that the reliability data pcnt results in an overlap region with low reliability (the minimum value is not detected and the reliability data pcnt = 0 or a position where a plurality of extreme values are obtained. Reliability data pcnt2), and the reliability data pcnt of the positional deviation amount data dyb obtained in the overlap area around the overlap area (located on the left and right of the other end). It corrects to the amount of position shift of the overlap area considered to have high reliability. The correction position generation unit 451 replaces the overlap region with high reliability only with the overlap region adjacent to one side, and replaces it with the average value when both have overlap regions with high reliability. Etc. The correction position generation unit 451 outputs the generated correction position deviation amount data TNC to the combined position determination unit 452 and the comparison unit 454.

  The one line position holding unit 453 holds (stores) the amount of positional deviation corrected by the combined position determination unit 452 for one line. The comparison unit 454 compares the post-correction positional deviation amount preDt output from the one-line position holding unit 453 with the value of the corrected positional deviation amount data TNC output from the correction position generation unit 451, and compares the result. DifC is output. In other words, the comparison unit 454 detects a change in the positional deviation amount output from the positional deviation amount one line before.

  The combined position determination unit 452 outputs either the positional deviation amount data dyb output from the positional deviation estimation unit 43 or the corrected positional deviation amount data TNC output from the correction position generation unit 451 from the comparison unit 454. The selected data is selected according to the comparison result DifC, and the selected data is output as the corrected positional deviation amount Dt. When the comparison result DifC indicates that the change from the positional deviation amount one line before is small, the combined position determination unit 452 selects the corrected positional deviation amount data TNC and outputs it as the corrected positional deviation amount Dt. To do. Thereby, the corrected positional deviation amount Dt is corrected to a value more reflecting the reliability.

  In normal reading, the amount of positional deviation between the line sensors arranged in the main scanning direction has substantially the same value, so it can be said that there is a correlation in the horizontal direction (main scanning direction). Therefore, the correction position generation unit 451 in the horizontal correlation position correction unit 45 reads if the positional deviation amount of the adjacent overlap region is corrected based on the positional deviation amount data dyb whose reliability is high by the reliability data pcnt. It becomes possible to reduce the influence of time jitter or dust attached to the optical system. In addition, fluctuations in the amount of positional deviation detected on the previous line (positional deviation amount preDt after one line output outputted from the one-line position holding unit 453) are also affected by jitter at the time of reading or dust attached to the optical system. If there is no influence, it is small, and by using the result of the comparison unit 454, the lateral correlation position correction unit 45 can generate a positional deviation amount with higher reliability.

  The corrected misregistration amount Dt output from the lateral correlation position correction unit 45 corrects the misregistration amount of the overlap region having low reliability by the reliability data pcnt with the misregistration amount of the overlap region having high reliability. Therefore, there is no false detection, and the misalignment amount Dt corrected with good accuracy can be obtained, and the influence of jitter at the time of reading or dust adhering to the optical system is reduced, and misdetection of misalignment amount can be performed. Therefore, it is possible to obtain the amount of image misregistration with good accuracy.

  The combined position determination unit 452 uses either the positional deviation amount data dyb output from the positional deviation estimation unit 43 or the corrected positional deviation amount data TNC output from the correction position generation unit 451 as the comparison result DifC. Accordingly, the case of selection has been described, but the selection by the coupling position determination unit 452 is not limited to such a method. For example, assuming that the comparison result DifC is a value that changes from 0 according to the difference, the coupling position determination unit 452 adapts the positional deviation amount data dyb and the corrected positional deviation amount data TNC at a ratio according to the value of the comparison result DifC. It is also possible to mix (add) and output the corrected positional deviation amount.

  In addition, the correction position generation unit 451 has an overlap region with low reliability (reliability data pcnt = 0 without detecting the minimum value, or a value equal to or higher than reliability data pcnt2 having a plurality of extreme positions. However, when the reliability data pcnt has a plurality of extreme positions, correction may be made so as to mix with the amount of misalignment in the vicinity.

<< 1-7 >> Coupling Processing Unit 46
The combination processing unit 46 receives the corrected positional deviation amount Dt output from the lateral correlation position correcting unit 45. The combination processing unit 46 calculates the read position RP of the image data based on the corrected misregistration amount Dt, reads the image data M46 corresponding to the read position from the image memory 41, and uses the corrected misregistration amount Dt. Based on this, processing for shifting the image data is performed, and the data in the overlap region of the image data is combined.

FIG. 14 is an explanatory diagram illustrating an example of a combining operation in the combining processing unit 46 according to the first embodiment. FIGS. 15A and 15B are explanatory diagrams illustrating another example of the coupling operation in the coupling processing unit 46 according to the first embodiment. As shown in FIG. 14, the line sensor _21E 1 located even-numbered, _..., 21E k, ..., data corresponding to 21E _n, may be shifted position by position shift amount Dt content after correction, as shown in FIG. 15 (a) and (b), the line sensor _21O 1 located odd, _..., 21O k, ..., and data corresponding to 21O _n, a line sensor _21E 1 located even-numbered, ..., 21E _k ,..., 21E _n may be shifted so that the sum of both the positional shift amounts of the data corresponding to 21E _n is equal to the corrected positional shift amount Dt. Figure 15 (a) in, the similarity calculating unit image data at the position Y _m of 42 read the sub-scanning direction as a reference line (Y direction), the amount positional deviation after the correction by the line sensor adjacent Dt min and shifting to allocate, in FIG. 15 (b), the data value min apart position allocating positional deviation amount Dt content after correction in the adjacent line sensors, are shifted to the position of the line Y _m.

As described above, the combination processing unit 46 calculates the read position RP of the image data based on the corrected positional deviation amount Dt, reads the image data M46 corresponding to the read position from the image memory 41, and sets the odd number. line sensor _21O 1 _{located, ..., 21O k, ...,} 21O n data and the line sensor _21E 1 located _{even-numbered,} ..., 21E k, ..., by combining the overlapping region data 21E _n overlap Image data D46 is generated. In the lateral correlation position correction unit 45, the corrected positional deviation amount Dt is calculated by using the reliability data pcnt output from the reliability determination unit 44 to determine the positional deviation amount in the overlap region with low reliability as another adjacent value. Since correction is performed based on the positional deviation amount of the highly reliable area in the overlap area and the positional deviation amount Dt after correction is obtained, the influence of jitter at the time of reading or dust attached to the optical system is reduced, It is obtained as data indicating the amount of positional deviation in the sub-scanning direction with good accuracy without erroneous detection. Therefore, if the readout position RP of the image data is calculated based on the corrected positional deviation amount Dt, the readout position corresponding to each line can be obtained accurately with good accuracy.

  In the image processing unit 4, the similarity calculation unit 42 calculates the similarity, the reliability determination unit 44 determines the reliability data pcnt from the similarity data Dist, and the lateral correlation position correction unit 45 determines the reliability data pcnt. Thus, the misalignment amount in the overlap region with low reliability is corrected based on the misalignment amount of the region with high reliability in the other adjacent overlap regions, and the corrected misalignment amount Dt is combined. The processing unit 46 reads the image data based on the corrected positional deviation amount Dt, and outputs the combined image data D46. The image processing unit 4 sequentially performs such processing in the sub-scanning direction (Y direction).

FIG. 16 is a diagram conceptually showing the image data D46 output from the combination processing unit 46 of the first embodiment. FIG. 16 shows an image obtained by combining the images in FIG. 4C, FIG. 5C, FIG. 6, and FIG. The combination processing unit 46 can correct the positional deviation amount in the sub-scanning direction (Y direction) and output the same image as the original 60 shown in FIGS. 4B and 5B. Particularly, in the case shown in FIG. 5 (c) or FIG. 7, the line sensor _21O 1 located odd, _..., 21O k, ..., the image data and the line sensor _21E 1 located to the even-numbered 21O _n, ..., Although the image data of 21E _k ,..., 21E _n are shifted in the sub-scanning direction (Y direction), the same image as that of the original 60 shown in FIG.

There is no false detection, and a read position is obtained from the corrected positional deviation amount Dt with good accuracy, and image data is obtained by using the image data of the position shifted by the value by the corrected positional deviation amount Dt and the surrounding lines of the position. because it produces a D46, the line sensor _21O 1 located _odd, ..., 21O k, ..., the line sensor _21E 1 located to the even-numbered and _{21O n, ..., 21E k,} ..., the sub-scanning direction 21E _n The misalignment is corrected, and the overlapping area images that have been read in duplicate are combined.

FIGS. 17A and 17B are diagrams illustrating an example in which the position of the document 60 with respect to the glass surface 26 changes during conveyance of the imaging unit 2. In the position _{Y m} in the sub-scanning direction (Y-direction), the document 60 is floated from the glass surface 26, in the position Yu, document 60 is adhered to the glass surface 26. At this time, the level difference caused by the performance variation for each line sensor or the difference of the reading condition is slightly changed depending on the position in the sub-scanning direction even in the image data by the same line sensor. Since the imaging unit 2 sequentially processes image data at each position in the sub-scanning direction (Y direction), even if the position of the document 60 changes during conveyance or the level value fluctuates, image processing is performed. The unit 4 determines the reliability from the image data of the overlap area at each position, and uses the position shift amount of the overlap area adjacent in the horizontal direction in the main scanning direction and the detected position shift amount of the previous line. Since the amount of misregistration at each position is calculated, the amount of misregistration can be obtained with good accuracy and images can be combined correctly. The line sensor _21O 1 located odd, _..., 21O k, ..., the line sensor _21E 1 located to the even-numbered and _{21O n, ..., 21E k,} ..., weight shift individually among all the 21E _n Therefore, even if the position of the document 60 with respect to the glass surface 26 is changed in the main scanning direction (X direction), the images can be combined correctly.

<< 1-8 >> Effect As described above, according to the image reading apparatus 1, the image processing apparatus 4, and the image processing method according to the first embodiment, the similarity calculation unit 42 uses the reference data MO and the comparison data. Similarity data (correlation data) Dist is calculated by comparing with ME, and the positional deviation estimation unit 43 calculates the positional deviation amount corresponding to the position of the comparison data with the highest similarity as the positional deviation amount data dyb. The reliability determination unit 44 determines the reliability of the positional deviation amount from the similarity data Dist to obtain the reliability data pcnt. The lateral correlation position correction unit 45 uses the reliability data pcnt to reduce the overlap with low reliability. The misregistration amount dyb in the region is corrected based on the misregistration amount of the region with high reliability among the other adjacent overlap regions, and the corrected misregistration amount Dt is obtained. The position of the read image (divided image) corresponding to the line sensor is shifted based on the corrected positional deviation amount Dt to generate composite image data obtained by combining a plurality of divided images. Therefore, it is possible to reduce the influence of jitter at the time of reading or the dust attached to the optical system, and to calculate a corrected positional deviation amount Dt that indicates the positional deviation amount with good accuracy without erroneous detection. In addition, since it is possible to generate composite image data by using the positional deviation amount Dt after correction with good accuracy without erroneous detection, high-quality synthetic image data corresponding to the object to be read can be generated. can do.

In the above description, the image processing unit 4, as described in FIG. 6 and FIG. 7 in the similarity calculation unit 42, the reference data MO is the digital data DI corresponding to the line sensors 21O _k of (O _k) The comparison data ME corresponds to the image data in the overlap region, and the comparison data ME is the image data in the overlap region of the digital data DI (E _k ) corresponding to the line sensor 21E _k . For example, the reference data MO is made to correspond to the image data in the overlap region of the digital data DI (E _k ) corresponding to the line sensor 21E _k , and the comparison data ME is made to the digital data DI (O _k ) corresponding to the line sensor 21O _k . The similarity data Dist may be calculated by comparing the reference data MO and the comparison data ME in correspondence with the image data in the overlap region. Further, the overlap region dr of the image data DI (O _k or E _k ) by the line sensor 21O or 21E may be used as reference data, and the overlap region dl of the adjacent line sensors may be used as comparison data. If the reference data MO and the comparison data ME having a predetermined number of lines can be obtained from the image data in the overlap area in which adjacent line sensors are read in duplicate with respect to the image data in the overlap area, The same effect as in the first mode is obtained.

<< 2 >> Embodiment 2
In the image reading device 1, the image processing device 4, and the image processing method according to the first embodiment, the reliability determination unit 44 (FIGS. 1 and 12) compares the value of the similarity data Dist with the threshold value Ndy, A candidate for the position where the value of the similarity data Dist is smaller than the threshold value Ndy (the position data Mpo) is obtained, and the position having the extreme value (extreme value determination result LMd and the similarity data Dsl at that position) And the reliability pcnt of the positional deviation amount is set. On the other hand, in the image reading device 1, the image processing device 4, and the image processing method according to the second embodiment of the present invention, the reliability determination shown in FIG. 18 is used instead of the reliability determination unit 44 (FIG. 12). Part 44b is used. The second embodiment is the same as the first embodiment except that the reliability determination unit 44 (FIG. 12) is replaced with the reliability determination unit 44b of FIG. Therefore, FIG. 1 is also referred to when describing the second embodiment.

  FIG. 18 is a block diagram schematically illustrating the configuration of the reliability determination unit 44b of the image reading apparatus 1 and the image processing apparatus (image processing unit) 4 according to the second embodiment. 18, components that are the same as or correspond to the components shown in FIG. 12 are assigned the same reference numerals as those in FIG. As shown in FIG. 18, the reliability determination unit 44b in the image processing unit 4 of the image reading apparatus 1 according to the second embodiment includes a detection range dividing unit 446, a minimum similarity detection unit 447, and an extreme value detection unit. 443b and a reliability setting unit 445. The configuration and operation of the reliability setting unit 445 are the same as those shown in the first embodiment.

  The reliability determination unit 44b divides the similarity data Dist in the positional deviation amounts dY of the plurality of lines in the search range (dY = −y to + y) output from the similarity calculation unit 42 into a plurality of small ranges, A position where the value of the similarity data Dist becomes the minimum value in each of the plurality of small ranges is detected. Then, the reliability determination unit 44b determines whether or not the position of the minimum value in the small range is an extreme value of the value of the similarity data Dist from the change in the minimum value in the adjacent small ranges among the plurality of small ranges. The candidate of the position where the value of the similarity data Dist is small and becomes the minimum is obtained.

  In FIG. 18, the similarity data Dist in the positional deviation amounts dY of a plurality of lines within the search range (dY = −y to + y) output from the similarity calculation unit 42 input to the reliability determination unit 44b is detected. The data is input to the range dividing unit 446.

  FIG. 19 is a diagram illustrating the relationship between the similarity data and the positional deviation amount in the sub-scanning direction for explaining the reliability determination operation in the reliability determination unit 44b. The detection range dividing unit 446 divides the search range (dY = −y to + y) for the positional deviation amount dY into a plurality of small ranges (divided detection ranges), and obtains similarity data Dist in each of the plurality of small ranges. And output to the minimum similarity detection unit 447. For example, as shown in FIG. 19, the search range (dY = −y to + y) of the positional deviation amount dY is divided into eight small ranges bn (n = 1, 2,..., 8), that is, the small ranges b1 to b1. Divide into b8.

  The minimum similarity detection unit 447 obtains the position where the value of the similarity data Dist is the smallest and the minimum in the similarity data Dist within the plurality of small ranges b1 to b8 divided by the detection range dividing unit 446. The position data b_Mpo and the minimum similarity data Dist value Mcor are output.

  The extreme value detection unit 443b receives the data b_Mpo and the value Mcor of the minimum similarity data Dist at the position where the value of the similarity data Dist is the smallest in the plurality of small ranges b1 to b8. The extreme value detection unit 443b detects a change in the minimum similarity data value Mcor in the adjacent small ranges bn−1 and bn + 1 for a certain small range bn, and the extreme value at which the similarity data changes from decreasing to increasing. It is detected (whether it is the minimum value). When the extreme value is detected, the extreme value detection unit 443b outputs the extreme value determination result bLMd indicating the position where the extreme value is obtained and the similarity data bDsl of the position. In addition, when there is no extreme value, the extreme value detection unit 443b outputs information indicating no extreme value as the extreme value determination result bLMd.

  As described above, by dividing the search range (dY = −y to + y) of the positional deviation amount dY into a plurality of small ranges and determining the change (extreme value) of the value of the similarity data Dist, fine image data is obtained. It is possible to determine the extreme value for determining the reliability by reducing the influence of noise mixed in the.

  The reliability setting unit 445 receives the extreme value determination result bLMd output from the extreme value detection unit 443b and the similarity data bDsl of the position, sets the reliability of the positional deviation amount, and the reliability data indicating the reliability Output pcnt. The operation of the reliability setting unit 445 in FIG. 18 is the same as the operation of the reliability setting unit 445 in FIG.

  The reliability setting unit 445 outputs reliability data pcnt indicating the reliability of the positional deviation amount based on the extreme value determination result bLMd and the similarity data bDsl of the position. For this reason, even if the similarity data Dist changes from the original value due to the influence of jitter at the time of reading or dust adhering to the optical system, the positional deviation amount is calculated using the reliability data pcnt. Can be sought.

  Since the misalignment amount of the overlap region with low reliability is corrected by the misalignment amount of the overlap region with high reliability based on the reliability data pcnt, the lateral correlation position correction unit 45 is good with no false detection. The position deviation amount Dt corrected with high accuracy can be obtained, the influence of jitter at the time of reading or the dust attached to the optical system is reduced, and there is no misdetection of the position deviation amount, and the image position deviation amount with good accuracy. Dt can be obtained.

  As described above, according to the image processing unit 4 according to the second embodiment, the reliability determination unit 44b determines the reliability of the positional deviation amount from the similarity data Dist and obtains the reliability data pcnt. The lateral correlation position correction unit 45 converts the positional deviation amount dyb in the overlap region with low reliability into the positional deviation amount of the region with high reliability in the adjacent overlapping regions based on the reliability data pcnt. Based on the corrected positional deviation amount Dt, the position of the divided image is shifted based on the corrected positional deviation amount Dt to generate combined image data. Therefore, it is possible to reduce the influence of jitter at the time of reading or the dust attached to the optical system, and to calculate a corrected positional deviation amount Dt indicating a positional deviation amount with good accuracy without erroneous detection. In addition, since it is possible to generate composite image data by using the positional deviation amount Dt after correction with good accuracy without erroneous detection, high-quality synthetic image data corresponding to the object to be read can be generated. can do.

<< 3 >> Embodiment 3
In the image reading apparatus 1, the image processing apparatus 4, and the image processing method according to the first embodiment, the lateral correlation position correction unit 45 (FIGS. 1 and 13) calculates the position shift amount preDt after correction for one line before. And is used to determine the combined position of the divided images. On the other hand, in the image reading device 1, the image processing device 4, and the image processing method according to the third embodiment of the present invention, the horizontal correlation shown in FIG. 20 is used instead of the horizontal correlation position correction unit 45 (FIG. 13). A position correction amount correction position is generated using the position correction unit 45b, and a corrected position shift amount Dt is obtained. The third embodiment is the same as the first embodiment except that the horizontal correlation position correction unit 45 (FIG. 13) is replaced with the horizontal correlation position correction unit 45b of FIG. Therefore, FIG. 1 is also referred to when describing the third embodiment.

  FIG. 20 is a block diagram schematically showing the configuration of the lateral correlation position correction unit 45b of the image reading device 1 and the image processing device (image processing unit) 4 according to the third embodiment. 20, components that are the same as or correspond to the components shown in FIG. 13 are given the same reference numerals as those in FIG. As illustrated in FIG. 20, the lateral correlation position correction unit 45 b includes a correction position generation unit 451, and a comparison unit 454 b that compares the positional deviation amount dyb with the corrected positional deviation amount data TNC output from the correction position generation unit 451. And a coupling position determination unit 452b. The configuration and operation of the correction position generation unit 451 are the same as those in the first embodiment.

  The corrected position generation unit 451 receives the reliability data pcnt output from the reliability determination unit 44 and the positional deviation amount data dyb output from the positional deviation estimation unit 43. When the reliability data pcnt results in an overlap region with low reliability, the correction position generation unit 451 uses the positional deviation amount data dyb obtained in the overlap region around the overlap region to calculate reliability data pcnt. Then, correction is made to the position shift amount of the overlap region, which is considered to be highly reliable, and corrected position shift amount data TNC is generated. The comparison unit 454b compares the positional deviation amount data dyb output from the positional deviation estimation unit 43 with the value of the corrected positional deviation amount data TNC output from the corrected position generation unit 451, and the comparison result indicating the result of this comparison DifCb is output. That is, the comparison unit 454b detects a difference between the value of the correction position deviation amount data TNC indicating the correction position and the value of the position deviation amount data dyb output from the position deviation estimation unit 43.

  The combined position determination unit 452b outputs either the positional deviation amount data dyb output from the positional deviation estimation unit 43 or the corrected positional deviation amount data TNC output from the correction position generation unit 451 from the comparison unit 454b. Is selected based on the comparison result DifCb, and is output as a corrected positional deviation amount Dt. The combination position determination unit 452b selects the correction position deviation amount data TNC when the difference from the position deviation amount before and after correction is large (for example, larger than a predetermined reference value) based on the comparison result DifCb. As a result, the combined position determination unit 452b can correct the positional deviation amount by removing the isolated point where the positional deviation amount dyb temporarily fluctuates and the value of the position or similarity data Dist has changed.

  The corrected misregistration amount Dt output from the lateral correlation position correction unit 45b is obtained by using the reliability data pcnt to calculate the misregistration amount of the overlap region with low reliability as the misregistration amount of the overlap region with high reliability. It is corrected. Therefore, in the third embodiment, it is possible to reduce the influence of jitter at the time of reading or dust attached to the optical system, so that the misregistration of the misregistration amount is not detected, and the misregistration amount of the image can be obtained with good accuracy.

  As described above, in the third embodiment, the lateral correlation position correction unit 45b uses the reliability data pcnt to set the positional deviation amount dyb in the overlap region with low reliability to another adjacent overlap region. Is corrected based on the positional deviation amount of the region with high reliability, and is the corrected positional deviation amount Dt. The position of the divided image is shifted based on the corrected positional deviation amount Dt, and the combined image Data is being generated. Therefore, it is possible to reduce the influence of jitter at the time of reading or the dust attached to the optical system, and to calculate a corrected positional deviation amount Dt indicating a positional deviation amount with good accuracy without erroneous detection. In addition, since it is possible to generate composite image data by using the positional deviation amount Dt after correction with good accuracy without erroneous detection, high-quality synthetic image data corresponding to the object to be read can be generated. can do.

<< 4 >> Embodiment 4
In the image reading device 1, the image processing device 4, and the image processing method according to the first and third embodiments, the image processing unit 4 uses the lateral correlation position correction unit 45 (FIG. 13) or 45b (FIG. 20). Explained. On the other hand, in the image reading device 1, the image processing device 4, and the image processing method according to the fourth embodiment of the present invention, the image processing unit 4 has the lateral correlation position correction unit 45 (FIG. 13) or 45b (FIG. 20). 21), a correction position for the amount of positional deviation is generated using the lateral correlation position correction unit 45c shown in FIG. 21, and the corrected amount of positional deviation is obtained. The fourth embodiment is the same as the first or third embodiment except that the horizontal correlation position correction unit 45 (FIG. 13) or 45b (FIG. 20) is replaced with the horizontal correlation position correction unit 45c of FIG. Therefore, FIG. 1 is also referred to in the description of the fourth embodiment.

  FIG. 21 is a block diagram schematically showing the configuration of the lateral correlation position correcting unit 45c of the image reading device 1 and the image processing device (image processing unit) 4 according to the fourth embodiment. In FIG. 21, the same or corresponding components as those shown in FIG. 13 are denoted by the same reference numerals as those in FIG. As shown in FIG. 21, the horizontal correlation position correction unit 45 c includes a change amount calculation unit 611, a corrected change amount generation unit 612, a change amount addition unit 613, a threshold determination unit 614, and a combined position determination unit 615. 1 line position holding unit 453. The configuration and operation of the 1-line position holding unit 453 are the same as those in the first embodiment.

  The one-line position holding unit 453 in FIG. 21 holds (stores) the result of correcting the positional deviation amount by the combined position determining unit 615 for one line. This operation is the same as the operation of the one-line position holding unit 453 in the lateral correlation position correction unit 45 in FIG. 13 (Embodiment 1). The change amount calculation unit 611 is a difference value between the value of the positional deviation amount data dyb output from the positional deviation estimation unit 43 and the post-correction positional deviation amount preDt output from the one-line position holding unit 453. (Change amount) is calculated, and the calculated change amount dgap is output. That is, the change amount calculation unit 611 detects a change output from the position shift amount one line before the current position shift amount.

  The corrected change amount generation unit 612 receives the reliability data pcnt output from the reliability determination unit 44 and the change amount dgap by the change amount calculation unit 611. The correction change amount generation unit 612 outputs the change amount dgap as it is in the overlap region where the reliability is high and the minimum value is one based on the reliability data pcnt. The correction change amount generation unit 612 uses the reliability data pcnt to provide an overlap region with low reliability (reliability data pcnt = 0 without detection of the minimum value, or reliability having positions where a plurality of extreme values are obtained. Data pcnt2 or more), the change amount dgap obtained in the overlap area around the overlap area (located on the left and right of the other end), and the reliability is determined to be high by the reliability data pcnt. Correction is made to the change amount dgap of the lap region. If the overlap region with high reliability is only the overlap region adjacent to one side, the correction change amount generation unit 612 replaces the overlap amount with the change amount dgap of the overlap region. If the overlap region with high reliability is an overlap region adjacent to both sides, the correction change amount generation unit 612 may replace it with the average value of the change amounts dgap of these overlap regions. The correction change amount generation unit 612 outputs the generated correction change amount TNG to the change amount addition unit 613 and the threshold determination unit 614.

  The change amount addition unit 613 adds the correction change amount TNG output from the correction change amount generation unit 612 to the post-correction positional deviation amount preDt output from the one line position holding unit 453, and Correction position deviation amount data TNCb is calculated. The threshold determination unit 614 compares the value of the correction change amount TNG output from the correction change amount generation unit 612 with a predetermined threshold value, and outputs a comparison result flg. Since the correction change amount TNG is a value obtained based on the change amount output from the position shift amount one line before, the change of the corrected position shift amount from the previous line can be determined.

  The combined position determination unit 615 outputs, from the threshold determination unit 614, either the positional shift amount data dyb output from the positional shift estimation unit 43 or the corrected positional shift amount data TNCb output from the change amount adding unit 613. The selected comparison result flg is selected and output as a corrected positional deviation amount Dt. When the change amount is set to a small value by the comparison result flg (when the change amount is equal to or smaller than the threshold value), the combined position determination unit 615 selects the correction position deviation amount data TNCb. As a result, the corrected positional deviation amount Dt is a value reflecting the reliability.

  The corrected positional deviation amount Dt output from the horizontal correlation position correcting unit 45c is the amount of change in the overlap region with low reliability based on the reliability data pcnt with respect to the amount of change from the positional deviation amount one line before. By correcting with the amount of change in the overlap area with high reliability, the amount of misalignment in the overlap area with low reliability is corrected to the amount of misalignment in the overlap area with high reliability. Therefore, the positional deviation amount Dt corrected with good accuracy can be obtained, the influence of jitter at the time of reading or the dust attached to the optical system can be reduced, and there is no misdetection of the positional deviation amount, and the image can be obtained with good accuracy. The amount of displacement can be obtained.

  As described above, in the fourth embodiment, the lateral correlation position correction unit 45c uses the reliability data pcnt to set the positional deviation amount dyb in the overlap region with low reliability to another adjacent overlap region. The amount of misalignment is corrected based on the amount of change output from one line before the highly reliable area, and the amount of misalignment is Dt after correction, and division is performed based on the amount of misalignment Dt after correction. The image position is shifted to generate combined image data. Therefore, it is possible to reduce the influence of jitter at the time of reading or the dust attached to the optical system, and to calculate a corrected positional deviation amount Dt indicating a positional deviation amount with good accuracy without erroneous detection. In addition, since it is possible to generate composite image data by using the positional deviation amount Dt after correction with good accuracy without erroneous detection, high-quality synthetic image data corresponding to the object to be read can be generated. can do.

<< 5 >> Embodiment 5
In the image reading device 1, the image processing device 4, and the image processing method according to the first, third, and fourth embodiments, the image processing unit 4 has the lateral correlation position correction units 45 (FIG. 13), 45b (FIG. 20), And 45c (FIG. 21) have been described. In contrast, in the image reading device 1, the image processing device 4, and the image processing method according to the fifth embodiment of the present invention, the image processing unit 4 includes the lateral correlation position correction units 45 (FIG. 13) and 45b (FIG. 20). ) Or 45c (FIG. 21), a correction position of a positional deviation amount is generated by using a horizontal correlation position correction unit 45d as shown in FIG. 22, and the corrected positional deviation amount is obtained. The fifth embodiment is the same as the first, third, or fourth embodiment except that the horizontal correlation position correction unit 45, 45b, or 45c is replaced with the horizontal correlation position correction unit 45d of FIG. Therefore, FIG. 1 is also referred to in the description of the fifth embodiment.

  FIG. 22 is a block diagram schematically showing the configuration of the horizontal correlation position correcting unit 45d of the image reading device 1 and the image processing device (image processing unit) 4 according to the fifth embodiment. 22, components that are the same as or correspond to the components shown in FIGS. 1, 13, and 21 are given the same reference numerals as those in FIGS. 1, 13, and 21. As shown in FIG. 22, the horizontal correlation position correction unit 45d includes a change amount calculation unit 611, a weighting factor setting unit 621, a position average calculation unit 622, a comparison unit 623, a combined position determining unit (combined position interpolation unit). Processing unit) 624 and a one-line position holding unit 453. The configuration and operation of the change amount calculation unit 611 and the one-line position holding unit 453 are the same as those shown in the fourth embodiment.

  The horizontal correlation position correction unit 45d in FIG. 22 calculates a difference value (change amount) between the positional shift amount data dyb output from the positional shift estimation unit 43 and the corrected positional shift amount preDt one line before, Based on the amount of change and reliability data pcnt obtained in the overlap region in the periphery including the wrap region, the weight coefficient corresponding to the reliability data and the amount of change in each overlap region is set, and the obtained weight coefficient From this, the corrected positional deviation amount is obtained.

  The one-line position holding unit 453 holds the amount of positional deviation corrected by the combined position determining unit 624 for one line. This operation is the same as that of the lateral correlation position correction unit 45 in the first embodiment. The change amount calculation unit 611 is a difference value (change) between the positional deviation amount data dyb output from the positional deviation estimation unit 43 and the corrected positional deviation amount preDt one line before output from the one-line position holding unit 453. Amount) and the change amount dgap is output. In other words, a change from the positional deviation amount of the previous line is detected.

  The weighting coefficient setting unit 621 receives the reliability data pcnt output from the reliability determination unit 44 and the change amount dgap from the change amount calculation unit 611, and depends on the reliability data and the change amount in each overlap region. A weighting coefficient CIR is set. In the overlap region where the reliability is high by the reliability data pcnt and the minimum value is one, when the change amount dgap is small, the weight coefficient CIR = 1 is set so that the ratio is high, and the change amount dgap is large Decreases the weight coefficient CIR (for example, ½). When the reliability data pcnt results in an overlap region with low reliability (the reliability data pcnt = 0 without detecting the minimum value, or a value equal to or higher than the reliability data pcnt2 having a plurality of extreme positions) The weighting coefficient CIR is reduced (for example, 0). Note that the weight coefficient CIR may be set with reliability data pcnt = 0 and a value equal to or higher than reliability data pcnt2 having a plurality of extreme positions without detecting the minimum value, or when the change amount dgap is large. The weight coefficient CIR may be set to be smaller. The generated weight coefficient CIR is output to the position average calculation unit 622 and the combined position determination unit 624.

  The position average calculation unit 622 receives the positional deviation amount data dyb output from the positional deviation estimation unit 43, the reliability data output from the weighting factor setting unit 621, and the weighting factor CIR corresponding to the change amount, In the periphery of the overlap area (located on the left and right sides of the other end) within the predetermined range with the lap area as the center, the average displacement amount is obtained by weighted average processing of the displacement amount data dyb by the weight coefficient CIR. HAC is calculated. Since the average is based on the reliability data and the weighting coefficient CIR according to the amount of change, the value in the overlap region with low reliability is not reflected, and is replaced with the average value based on the positional deviation amount in the overlap region with high reliability. It is equivalent to. The average positional deviation amount HAC is output to the comparison unit 623 and the coupling position determination unit 624.

  The comparison unit 623 compares the positional deviation amount data dyb output from the positional deviation estimation unit 43 with the value of the average positional deviation amount HAC, and outputs a comparison result DifC2. In other words, the comparison unit 623 detects a difference between the correction position and the result obtained by the position deviation estimation unit.

  The combined position determination unit 624 includes the positional deviation amount data dyb output from the positional deviation estimation unit 43, the average positional deviation amount HAC output from the position average calculation unit 622, and the reliability output from the weighting factor setting unit 621. The data and the weighting coefficient CIR corresponding to the change amount are received, and the position shift amount Dt after correction is obtained by weighted interpolation of the position shift amount data dyb and the average position shift amount HAC based on the weight coefficient CIR in the overlap region. . At this time, if the comparison result DifC2 output from the comparison unit 623 has a large difference from the positional deviation amount before and after correction, the average positional deviation amount HAC may be selected as the corrected positional deviation amount Dt. As a result, it is possible to correct the positional deviation amount by removing the isolated point where the positional deviation amount dby fluctuates temporarily and the value of the position or similarity data Dist changes.

  The corrected positional deviation amount Dt output from the horizontal correlation position correcting unit 45d sets the weighting coefficient CIR according to the amount of change from the positional deviation amount one line before and the reliability data pcnt, and weights the positional deviation amount. In addition to performing averaging, the positional deviation amount Dt after correction based on the change output from the weighting coefficient and the positional deviation amount dyb is obtained by interpolation processing, thereby calculating the positional deviation amount of the overlap region with low reliability. Since the positional deviation amount of the overlap region with high reliability is corrected, the positional deviation amount Dt corrected with good accuracy can be obtained with no false detection, and jitter at reading or dust attached to the optical system can be obtained. Thus, the positional deviation amount of the image can be obtained with good accuracy without misdetection of the positional deviation amount.

  As described above, in the fifth embodiment, the lateral correlation position correction unit 45d sets the weighting coefficient CIR corresponding to the reliability data pcnt and performs weighted average of the positional deviation amount, and at the time of correction, the weighting coefficient Based on the change output from the positional deviation amount dyb, interpolation processing is performed to obtain a corrected positional deviation amount Dt. The position of the divided image is shifted based on the corrected positional deviation amount Dt, and the combined image Data is being generated. Therefore, it is possible to reduce the influence of jitter at the time of reading or the dust attached to the optical system, and to calculate a corrected positional deviation amount Dt indicating a positional deviation amount with good accuracy without erroneous detection. In addition, since it is possible to generate composite image data by using the positional deviation amount Dt after correction with good accuracy without erroneous detection, high-quality synthetic image data corresponding to the object to be read can be generated. can do.

<< 6 >> Embodiment 6
In the image reading device 1, the image processing device 4, and the image processing method according to the first, third, fourth, and fifth embodiments, the image processing unit 4 has the lateral correlation position correction units 45 (FIG. 13) and 45b (FIG. 20). ), 45c (FIG. 21), and 45d (FIG. 22) have been described. On the other hand, in the image reading device 1, the image processing device 4, and the image processing method according to the sixth embodiment of the present invention, the image processing unit 4 includes the lateral correlation position correction units 45 (FIG. 13) and 45b (FIG. 20). ), 45c (FIG. 21), instead of 45d (FIG. 22), a lateral correlation position correction unit 45e as shown in FIG. 23 is used to generate a correction position of the positional shift amount, and the corrected positional shift amount. Seeking. The sixth embodiment is the same as the first, third, fourth, or fifth embodiment except that the horizontal correlation position correction unit 45, 45b, 45c, or 45d is replaced with the horizontal correlation position correction unit 45e of FIG. is there. Therefore, FIG. 1 is also referred to in the description of the sixth embodiment.

  FIG. 23 is a block diagram schematically showing the configuration of the lateral correlation position correction unit 45e in the image reading device 1 and the image processing device (image processing unit) 4 according to the sixth embodiment. In FIG. 23, constituent elements that are the same as or correspond to those shown in FIGS. 1, 13, 21, and 22 are assigned the same reference numerals as those in FIGS.

  As shown in FIG. 23, the horizontal correlation position correction unit 45e includes a change amount calculation unit 611, a weighting factor setting unit 621, a change amount average calculation unit 631, a change amount comparison unit 632, and a change amount interpolation processing unit. 633, an interpolation change amount adding unit 634, and a one-line position holding unit 453. The configurations and operations of the change amount calculation unit 611, the weighting coefficient setting unit 621, and the 1-line position holding unit 453 are the same as those shown in the fifth embodiment. 23 obtains a difference value (change amount) between the positional deviation amount data dyb output from the positional deviation estimation unit 43 and the corrected positional deviation amount preDt one line before, Based on the amount of change and reliability data pcnt obtained in the overlap region in the periphery including the wrap region, the weight data corresponding to the reliability data and the amount of change in each overlap region is set, and the obtained weight The change amount is corrected from the coefficient, and the corrected positional deviation amount is obtained from the corrected change amount.

  The one-line position holding unit 453 holds the position shift amount corrected by the interpolation change amount adding unit 634 for one line. This operation is the same as the operation of the one-line position holding unit 453 in the lateral correlation position correction unit 45 in the first embodiment. The change amount calculation unit 611 is a difference value (change) between the positional deviation amount data dyb output from the positional deviation estimation unit 43 and the corrected positional deviation amount preDt one line before output from the one-line position holding unit 453. Amount) and the change amount dgap is output. That is, the change amount calculation unit 611 detects a change from the positional deviation amount of the previous line. The weighting coefficient setting unit 621 receives the reliability data pcnt output from the reliability determination unit 44 and the change amount dgap from the change amount calculation unit 611, and depends on the reliability data and the change amount in each overlap region. A weighting coefficient CIR is set. This operation is the same as the operation in the horizontal correlation position correcting unit 45d in the fifth embodiment.

  The change amount average calculation unit 631 receives the change amount dgap from the change amount calculation unit 611, the reliability data output from the weighting factor setting unit 621, and the weighting factor CIR according to the changing amount, and centers the overlap region. In other overlap regions (regions located on the left and right sides of the other end) within the predetermined range, the average change amount HAG is calculated by weighted average processing of the change amount dgap by the weighting coefficient CIR. Since the average is based on the reliability data and the weighting coefficient CIR corresponding to the amount of change, the value in the overlap region with low reliability is not reflected, and is replaced with the average value based on the change amount dgap in the overlap region with high reliability. It corresponds to. The average change amount HAG is output to the change amount comparison unit 632 and the change amount interpolation processing unit 633.

  The change amount comparison unit 632 compares the change amount dgap by the change amount calculation unit 611 with the value of the average change amount HAG, and outputs a result DifG as a result of this comparison. That is, the change amount comparison unit 632 detects the difference between the average change amount HAG and the change amount dgap.

  The change amount interpolation processing unit 633 receives the change amount dgap from the change amount calculation unit 611, the average change amount HAG, the reliability data output from the weighting factor setting unit 621, and the weighting factor CIR according to the changing amount. Based on the weighting coefficient CIR in the overlap region, the change amount dgap and the average change amount HAG are weighted and interpolated to obtain the corrected change amount NGC. At this time, when the difference between the change amounts before and after the correction is large according to the comparison result DifG output from the change amount comparison unit 632, the average change amount HAG may be selected and used as the corrected change amount NGC. As a result, the positional deviation amount dyb temporarily varies, and the isolated point where the value of the position or similarity data Dist has changed can be removed to correct the positional deviation amount.

  The interpolation change amount adding unit 634 adds the correction change amount TNG output from the change amount interpolation processing unit 633 to the post-correction position shift amount preDt output from the one line position holding unit 453. Then, the corrected positional deviation amount Dt is calculated.

  The corrected misalignment amount Dt output from the horizontal correlation position correcting unit 45e is set by setting a weight coefficient CIR according to the amount of change from the misalignment amount of the previous line and the reliability data pcnt. In addition to performing weighted averaging of the amount of change and interpolating the amount of change before and after correction from the weighting coefficient at the time of correction to obtain a corrected position shift amount Dt, the position shift amount of the overlap region with low reliability Is corrected to the positional deviation amount of the overlap region with high reliability. For this reason, there is no misdetection, and the misalignment amount Dt corrected with good accuracy can be obtained. The amount of image displacement can be obtained with good accuracy.

  As described above, in the sixth embodiment, the lateral correlation position correction unit 45e sets the weighting coefficient CIR according to the reliability data pcnt to perform the weighted average of the amount of change in the positional deviation amount and the correction. Sometimes the amount of change before and after correction is obtained from the weighting coefficient by interpolation processing to obtain a corrected positional deviation amount Dt, and the positions of the divided images are shifted based on this corrected positional deviation amount Dt to combine them. Generated image data. Therefore, it is possible to reduce the influence of jitter at the time of reading or the dust attached to the optical system, and to calculate a corrected positional deviation amount Dt indicating a positional deviation amount with good accuracy without erroneous detection. In addition, since it is possible to generate composite image data by using the positional deviation amount Dt after correction with good accuracy without erroneous detection, high-quality synthetic image data corresponding to the object to be read can be generated. can do.

<< 7 >> Embodiment 7
Part of the functions of the image reading apparatus 1 according to the first embodiment may be realized by a hardware configuration, or may be realized by a computer program executed by a microprocessor including a CPU (central processing unit). Good. When a part of the function is realized by a computer program, the microprocessor loads and executes the computer program from a computer-readable storage medium or by communication such as the Internet. Can be realized.

  FIG. 24 is a block diagram schematically showing a configuration when a part of the functions of the image reading apparatus 1b is realized by a computer program. As shown in FIG. 24, the image reading device 1b according to the seventh embodiment includes an imaging unit 2, an A / D conversion unit 3, and a calculation device 5. The arithmetic device 5 includes a processor 51 including a CPU, a random access memory (RAM) 52, a nonvolatile memory 53, a mass storage medium 54, and a bus 55. As the non-volatile memory 53, for example, a flash memory can be used. Further, as the large-capacity storage medium 54, for example, a hard disk (magnetic disk), an optical disk, or a semiconductor storage device can be used.

  The A / D conversion unit 3 has the same function as the A / D conversion unit 3 in FIG. 1, converts the electrical signal SI output from the imaging unit 2 into digital data, and stores the digital data in the RAM 52 via the processor 51. . The processor 51 can implement the functions of the image processing unit 4 by loading a computer program from the nonvolatile memory 53 or the large-capacity storage medium 54 and executing the loaded program.

  FIG. 25 is a flowchart schematically illustrating an example of processing performed by the arithmetic device 5 according to the seventh embodiment. As shown in FIG. 25, the processor 51 first reads out data in the overlap region of the image data, extracts the reference data MO and the comparison data ME having a predetermined number of lines, and compares them with the reference data MO. A similarity calculation process for comparing with the data ME is executed (step S1). Thereafter, the processor 51 executes a positional deviation amount estimation process to obtain positional deviation amount data (step S2). Further, the processor 51 determines the reliability of the positional deviation amount detected in each overlap region from the value of the similarity data Dist in the overlap region (step S3), and the reliability is low based on the determined reliability data. Lateral correlation position correction step as a correlation position correction step (correlation position correction processing) for correcting the position shift amount in the overlap region based on the position shift amount of a region with high reliability among other adjacent overlap regions (Horizontal correlation position correction processing) is performed to obtain a corrected positional deviation amount Dt (step S4). Finally, the processor 51 executes a combination process (step S5). Note that the processing in steps S1 to S5 by the arithmetic device 5 is the same as the processing performed by the image processing unit 4 in the first embodiment.

  As described above, according to the image reading device 1b according to the seventh embodiment, the similarity data Dist is calculated by comparing the reference data MO and the comparison data ME, and the position of the comparison data having the highest similarity is calculated. Is calculated from the similarity data Dist, and the reliability data pcnt indicating the reliability is obtained from the similarity data Dist. The misalignment amount dyb in the overlap region is corrected based on the misalignment amount of the region with high reliability in the other adjacent overlap regions, and is set as a misalignment amount Dt after correction. Based on the amount Dt, the position of the divided image is shifted to generate combined image data. Therefore, it is possible to reduce the influence of jitter at the time of reading or the dust attached to the optical system, and to calculate a corrected positional deviation amount Dt indicating a positional deviation amount with good accuracy without erroneous detection. In addition, since it is possible to generate composite image data by using the positional deviation amount Dt after correction with good accuracy without erroneous detection, high-quality synthetic image data corresponding to the object to be read can be generated. can do.

<< 8 >> Embodiment 8
In the first embodiment, FIG. 4 as (a), the one end (e.g., the left end) line sensor _21O 1 located odd counted from, _..., 21O k, ..., of 21O _n line sensor _21E 1 located to the even-numbered and the optical axis _{27O, ..., 21E k, ...} , and the optical axis 27E of 21E _n has been described a case where intersecting. In the eighth embodiment, one end (e.g., the left end) line sensor _21O 1 located odd counted from, _..., 21O k, ..., the line sensor located even-numbered and the optical axis 28O of 21O _{n 21E 1, ..., 21E k,} ..., not intersect with the optical axis 28E of 21E _n, it will be described parallel. The image reading apparatus according to the eighth embodiment is substantially the same as the image reading apparatus 1 according to the first embodiment except that the optical axes 28O and 28E are parallel. Therefore, FIG. 1 is also referred to in the description of the eighth embodiment.

FIGS. 26A and 26B are optical axes of line sensors 21O (21O ₁ ,..., 21O _k ,..., 21O _n ) located at odd-numbered positions in the imaging unit 2 of the image reading apparatus according to the eighth embodiment. The positional relationship between the original 60 as the object to be read and the line sensor when the optical axis 28E of the line sensor 21E (21E ₁ ,..., 21E _k ,..., 21E _n ) 28O and the even-numbered line sensors 21E is parallel. FIG. FIG. 26A shows a case where the document 60 is in close contact with the glass surface 26 which is the document table mounting surface, and FIG. 26B shows a case where the document 60 is slightly lifted away from the glass surface 26. Indicates.

In the image reading apparatus according to the eighth embodiment, when document 60 is in close contact with glass surface 26 as shown in FIG. 26A, document 60 is glass as shown in FIG. be any of the case away from the surface 26, the line sensor _21O 1 located odd, _..., 21O k, ..., the read image of the document 60 by 21O _n hardly changes, similarly, the even-numbered line sensor _21E 1 _located, ..., 21E k, ..., the read image of the document 60 by 21E _n is hardly changed. Also, when the imaging unit 2 is conveyed in the sub-scanning direction (Y-direction), the line sensor _21O 1 located _{odd, ..., 21O k, ...,} 21O n is the line sensor _21E 1 located even number, ..., 21E k, _..., compared to 21E _n, is to acquire an image of the same position temporally delayed, since the optical axis 28O and the optical axis 28E are parallel, the sub-scanning direction of the reading shift position reading is Can be obtained as a substantially constant amount YL. As the minute positional deviation amount, the deviation of the optical axis 28O or the optical axis 28E due to the attachment error of the line sensor or the like, and the temporal fluctuation of the conveyance speed (that is, speed fluctuation) ) Is included.

  In the eighth embodiment, as in the first embodiment, when there is jitter or optical system attached dust in the imaging unit 2, the image data in the overlap region in the image data DI is read for each line sensor. Difference in image data (difference in pixel data value) occurs, and in an image read in a certain period, the reading position is deviated from the original position, the image data value may temporarily differ, or images at different positions The similarity data Dist becomes a value that fluctuates from the original value, the position where the similarity is highest is temporarily shifted, or the value of the similarity data Dist increases (the similarity is low). Become).

FIG. 27 shows image data DI (O _k ) and DI (O _{k + 1} ) corresponding to the even-numbered line sensors 21O _k and 21O _{k + 1} when the original is read, and the odd-numbered line sensors 21E _k and 21E. image data _DI corresponding to _{k + 1} (E _k), shows the DI _{(E k + 1).} In each, the position (line) in the sub-scanning direction is shifted by ((fixed amount YL) + (shift bt)).

Therefore, the image processing unit 4, the line sensor _21O 1 located odd when writing to the image memory 41, _..., 21O k, ..., the image reading by 21O _n, or line sensor 21E ₁ located even number ,..., 21E _k ,..., 21E _n , one or both of the scanned images are shifted by a substantially constant amount YL in the sub-scanning direction. As a result, as shown in FIG. 28, the image data stored in the image memory 41 is stored in the image memory 41 with the position (line) in the sub-scanning direction being shifted by the positional shift amount bt due to the change in the conveyance speed. The

  Note that the processing of shifting by a certain amount YL is performed at the time of writing to the image memory 41. However, when the image data is read by the similarity calculation unit 42 or the combination processing unit 46, the position for reading the certain amount YL is read. Alternatively, the position may be obtained by adding the offset.

  Hereinafter, the image processing unit 4 obtains the positional deviation amount bt in the sub-scanning direction and combines the images. The image data in the overlap area is compared with the reference data MO and the comparison data having a predetermined number of lines. ME is obtained, and the similarity is calculated by comparing the reference data and the comparison data, and the misregistration amount corresponding to the position of the comparison data having the highest similarity is calculated, and the misregistration amount Dist is used to calculate the misregistration amount. The reliability data pcnt is determined, and the reliability data pcnt is used to calculate the positional deviation amount dyb in the overlap area with low reliability from the adjacent other overlap areas. The image data is read out from the image memory 41 based on the corrected positional deviation amount Dt as the corrected positional deviation amount Dt. Binding processing. This configuration and operation are the same as those in the first embodiment.

  As described above, in the apparatus and method of the eighth embodiment, at the time of imaging by the imaging unit 2, the conveyance unit when moving either one or both of the document 60 and the imaging unit 2 in the sub-scanning direction. Even in the case where there is a temporal fluctuation (that is, speed fluctuation) in the transport speed due to 24, as in the case of the first embodiment, the influence of jitter at the time of reading or optical system dust is reduced. It is possible to calculate a corrected positional deviation amount Dt indicating a positional deviation amount with good accuracy without detection. Further, according to the apparatus and method of the eighth embodiment, since it is possible to generate composite image data using the positional deviation amount Dt after the correction, the high-quality synthesis corresponding to the object to be read. Image data can be generated.

<< 9 >> Embodiment 9
In the first embodiment, as shown in FIG. 2A, a plurality of line sensors 21O ₁ , 21E ₁ ,... Are arranged in a staggered manner, and the ends of adjacent line sensors are arranged in the main scanning direction. The case of having overlapping overlap areas (for example, sr, sl) has been described. However, if the plurality of line sensors are arranged so that the imaged areas to be read by adjacent line sensors have a region so that partially overlaps in the main scanning direction, The line sensor may be arranged by an arrangement method other than the staggered arrangement (for example, a linear arrangement).

Figure 29 is a line sensor 21E _k and 21O _k of the imaging unit 2 of the image reading apparatus according to the ninth embodiment is, in a straight line in the main scanning direction, partly overlap in the main scanning direction is the imaging region of the read object FIG. 6 is a schematic side view showing a positional relationship between a document 60 as a read object and a line sensor when the arrangement is configured to have a region so. 29, the plurality of line sensors 21O ₁ , 21E ₁ ,..., 21O _k , 21E _k ,..., 21O _n , 21E _n are linearly arranged in the main scanning direction. Here, n is an integer of 2 or more, and k is an integer of 1 to n. Then, by disposing the lenses 29O and 29E between the document 60 and the imaged region to be read, the imaged region read by the adjacent line sensor has a region so partially overlapping in the main scanning direction. ing. In the image reading apparatus according to the ninth embodiment, a plurality of line sensors are arranged in a straight line, and a plurality of lenses 29O and 29E corresponding to the plurality of line sensors are arranged in a straight line, so that reading is performed by adjacent line sensors. The image reading apparatus 1 according to the first embodiment is substantially the same as the image reading apparatus 1 according to the first embodiment except that adjacent imaged areas to be overlapped partially in the main scanning direction. Therefore, the image processing unit according to the ninth embodiment is substantially the same as the image processing unit 4 according to the first embodiment.

  According to the image reading apparatus according to the ninth embodiment, even if the plurality of line sensors are arranged in a straight line and the imaged area has an area so that it partially overlaps in the main scanning direction. As in the case of the first embodiment, the influence of the jitter at the time of reading or the dust attached to the optical system is reduced, and the corrected misregistration amount Dt indicating the misregistration amount with good detection is calculated. can do. Further, according to the image reading apparatus according to the ninth embodiment, since it is possible to generate composite image data using the positional deviation amount Dt after the correction, the high-quality synthesis corresponding to the read object. Image data can be generated.

  The image reading apparatus and the image processing apparatus can be configured and the image processing method can be implemented by appropriately combining any of the configurations and processes described in the first to ninth embodiments. .

  The present invention is applied to an image reading apparatus such as a copying machine, a scanner, and a facsimile, an image processing apparatus built in the image reading apparatus, an image processing method executed by the image processing apparatus, and a program executed by the image processing apparatus. can do. The program to which the present invention is applied can also be applied to an information processing apparatus such as a personal computer that is communicably connected to an image reading apparatus such as a copying machine, a scanner, and a facsimile.

1,1b image reading apparatus, second imaging unit, 3 A / D conversion unit, 4 an image processing section (image processing apparatus), 5 calculation unit, 20 sensor _{substrate, 21O, 21O 1, ...,} 21O k, ..., 21O n line sensor located _{odd, 21E, 21E 1, ...,} 21E k, ..., the line sensor located 21E _n even-numbered, 25 illumination source, a photoelectric conversion element for 26R red light, photoelectrically for 26G green red light Conversion element, 26B photoelectric conversion element for blue light, 27O, 28O optical axis of the odd-numbered line sensor, 27E, 28E optical axis of the even-numbered line sensor, 41 image memory, 42 similarity calculation unit, 43 misalignment estimation unit, 46 joint processing unit, 44, 44b reliability determination unit, 45, 45b, 45c, 45d, 45e lateral correlation position correction unit (correlation position correction unit) 51 processor, 52 RAM, 53 non-volatile memory, 54 mass storage device, 60 document, 441 threshold setting unit, 442 similarity comparison unit, 443, 443b extreme value detection unit, 445, 445b reliability setting unit, 446 detection range Dividing unit, 447 minimum similarity detection unit, 451 correction position generation unit, 452, 615 combination position determination unit, 453 1 line position holding unit, 454, 454b comparison unit, 611 change amount calculation unit, 612 correction change amount generation unit, 613 Change amount addition unit, 614 Threshold value determination unit, 621 Weight coefficient setting unit, 622 Position average calculation unit, 623 Comparison unit, 624 Combined position determination unit, 631 Change amount average calculation unit, 632 Change amount comparison unit, 633 Change amount interpolation processing unit, 634 interpolation variation adding _{unit, A 1,1, ..., A k} , k, A k, k + 1, A k + 1, _{+1, ..., A n, n} overlap region, D46 image data, DI digital data (image data), Dist similarity data, the transport direction of Dy imaging unit, dyb position shift amount data, Dt corrected position deviation amount data, M46 Image data, MO reference data, ME comparison data, pcnt reliability data, RP read position data, SI electrical signal, sr line sensor right end area, sl line sensor left end area.

Claims (9)

A plurality of line sensors arranged in the main scanning direction are generated by an imaging unit arranged so that end portions of reading ranges of adjacent line sensors of the plurality of line sensors overlap each other. In an image processing apparatus that processes an image signal,
An image memory for storing image data based on the image signal;
From the image data in the overlap area of the image data read out from the image memory, reference data at a reference position in the sub-scanning direction and comparison data in an area overlapping the overlap area of the reference data The process of obtaining and comparing the reference data and the comparison data is performed for a plurality of positions where the position of the comparison data is moved in the sub-scanning direction, and the reference data and the plurality of positions in the sub-scanning direction are A similarity calculation unit that calculates similarity with comparison data and outputs similarity data indicating the similarity;
The position of the comparison data having the highest similarity among the comparison data at the plurality of positions in the sub-scanning direction is obtained from the similarity data, and the position having the highest similarity with the position in the sub-scanning direction of the reference data is obtained. A positional deviation estimation unit that calculates a positional deviation amount based on a difference from the position of the comparison data and outputs positional deviation amount data indicating the positional deviation amount;
A process of detecting an extreme value of the similarity data based on the value of the similarity data is performed, a reliability of the positional deviation amount in the overlap region is set based on the result of the process, and the reliability is indicated A reliability determination unit that outputs reliability data;
Based on the reliability data output from the reliability determination unit, the positional deviation amount data in the first region that is the overlap region is given a higher reliability than the reliability in the first region. A correlation position correction unit that corrects by positional deviation amount data in a second region that is another overlap region different from the first region;
Composite image data is generated by combining the image data read by the adjacent line sensors among the image data read from the image memory based on the positional deviation amount data corrected by the correlation position correction unit. An image processing apparatus comprising: a combination processing unit.   The image processing apparatus according to claim 1, wherein the second area includes at least one of an overlap area immediately adjacent to the first area. The second region includes at least one of an overlap region immediately adjacent to the first region and at least one of an overlap region adjacent to the second region from the first region. Item 3. The image processing apparatus according to Item 2. The reliability determination unit
An extreme value detection unit that performs a process of detecting an extreme value of the value of the similarity data in the comparison data at the plurality of positions in the sub-scanning direction;
A reliability setting unit that generates the reliability data based on a result of a process of detecting the extreme value;
The image processing apparatus according to claim 1, further comprising: The correlation position correction unit
Based on the reliability data, a correction position generation unit that generates correction position deviation amount data by interpolating the position deviation amount data between adjacent overlap areas;
A combined position determination unit for obtaining corrected positional deviation amount data for coupling from the positional deviation amount data and the corrected positional deviation amount in the overlap region;
Have
2. The position shift amount data in the overlap region is corrected based on the position shift amount data in the overlap region having the high reliability among other adjacent overlap regions. 5. The image processing device according to any one of items 1 to 4. The correlation position correction unit
A change amount calculation unit that calculates a change amount between the positional deviation amount data and the positional deviation amount data of one line before;
Based on the reliability data, a correction change amount generation unit that interpolates the change amount in the overlap region and another overlap region adjacent thereto, and generates a correction change amount;
A combined position determination unit that adds the correction change amount to the positional deviation amount data of the previous line and obtains corrected positional deviation amount data for coupling;
Have
The position shift amount data in the overlap region is corrected based on the position shift amount data in the overlap region having the high reliability of the other adjacent overlap regions. The image processing apparatus according to any one of 1 to 4. A plurality of line sensors arranged in the main scanning direction are generated by an imaging unit arranged so that end portions of reading ranges of adjacent line sensors of the plurality of line sensors overlap each other. An image processing method for processing an image signal,
A storing step of storing image data based on the image signal in an image memory;
From the image data in the overlap area of the image data read out from the image memory, reference data at a reference position in the sub-scanning direction and comparison data in an area overlapping the overlap area of the reference data The process of obtaining and comparing the reference data and the comparison data is performed for a plurality of positions where the position of the comparison data is moved in the sub-scanning direction, and the reference data and the plurality of positions in the sub-scanning direction are A similarity calculation step of calculating similarity with comparison data and outputting similarity data indicating the similarity;
The position of the comparison data having the highest similarity among the comparison data at the plurality of positions in the sub-scanning direction is obtained from the similarity data, and the position having the highest similarity with the position in the sub-scanning direction of the reference data is obtained. A positional deviation estimation step of calculating a positional deviation amount based on a difference from the position of the comparison data and outputting positional deviation amount data indicating the positional deviation amount;
A process of detecting an extreme value of the similarity data based on the value of the similarity data is performed, a reliability of the positional deviation amount in the overlap region is set based on the result of the process, and the reliability is indicated A reliability determination step for outputting reliability data;
Based on the reliability data output in the reliability determination step, the positional deviation amount data in the first area that is the overlap area is given a higher reliability than the reliability in the first area. A correlation position correction step for correcting by positional deviation amount data in the second area which is another overlap area different from the first area;
Composite image data is generated by combining the image data read by the adjacent line sensors among the image data read from the image memory based on the positional deviation amount data corrected in the correlation position correction step. An image processing method comprising: a combining processing step. A plurality of line sensors arranged in the main scanning direction, an image pickup unit arranged so as to have an overlap region in which ends of reading ranges of adjacent line sensors among the plurality of line sensors overlap each other;
An image memory for storing image data based on the image signal generated by the imaging unit;
From the image data in the overlap area of the image data read out from the image memory, reference data at a reference position in the sub-scanning direction and comparison data in an area overlapping the overlap area of the reference data The process of obtaining and comparing the reference data and the comparison data is performed for a plurality of positions where the position of the comparison data is moved in the sub-scanning direction, and the reference data and the plurality of positions in the sub-scanning direction are A similarity calculation unit that calculates similarity with comparison data and outputs similarity data indicating the similarity;
A position of comparison data having the highest similarity among the comparison data at the plurality of positions in the sub-scanning direction is obtained from the similarity data, and the position having the highest similarity with the position in the sub-scanning direction of the reference data is obtained. A positional deviation estimation unit that calculates a positional deviation amount based on a difference from the data position and outputs positional deviation amount data indicating the positional deviation amount;
A process of detecting an extreme value of the similarity data based on the value of the similarity data is performed, a reliability of the positional deviation amount in the overlap region is set based on the result of the process, and the reliability is indicated A reliability determination unit that outputs reliability data;
Based on the reliability data output from the reliability determination unit, the positional deviation amount data in the first region that is the overlap region is given a higher reliability than the reliability in the first region. A correlation position correction unit that corrects by positional deviation amount data in a second region that is another overlap region different from the first region;
Composite image data is generated by combining the image data read by the adjacent line sensors among the image data read from the image memory based on the positional deviation amount data corrected by the correlation position correction unit. An image reading apparatus comprising: a combination processing unit. A plurality of line sensors arranged in the main scanning direction are generated by an imaging unit arranged so that end portions of reading ranges of adjacent line sensors of the plurality of line sensors overlap each other. From the image data in the overlap area of the image data read from the image memory that stores image data based on the image signal, to the reference data of the reference position in the sub-scanning direction and the overlap area of the reference data The comparison data in the overlapping region is obtained, and the process of comparing the reference data and the comparison data is performed for a plurality of positions where the position of the comparison data is moved in the sub-scanning direction, A level of similarity between the position in the sub-scanning direction and the comparison data is calculated and similarity data indicating the degree of similarity is output And the degree calculation process,
The position of the comparison data having the highest similarity among the comparison data at the plurality of positions in the sub-scanning direction is obtained from the similarity data, and the position of the reference data in the sub-scanning direction and the comparison data having the highest similarity. A positional deviation estimation process for calculating a positional deviation amount based on the difference between the position and the position deviation amount data indicating the positional deviation amount;
A process of detecting an extreme value of the similarity data based on the value of the similarity data is performed, a reliability of the positional deviation amount in the overlap region is set based on the result of the process, and the reliability is indicated Reliability determination processing for outputting reliability data;
Based on the reliability data output in the reliability determination process, the positional deviation amount data in the first region that is the overlap region is given a higher reliability than the reliability in the first region. A correlation position correction process for correcting by positional deviation amount data in the second area which is another overlap area different from the first area;
Composite image data is generated by combining the image data read by the adjacent line sensors among the image data read from the image memory based on the positional deviation amount data corrected by the correlation position correction processing. A program that causes a computer to execute the joining process.

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